Examples with solutions for Area of a Rectangle: Using additional geometric shapes

Exercise #1

The rectangle ABCD is shown below.

BD=25,BC=7 BD=25,BC=7

Calculate the area of the rectangle.

AAABBBCCCDDD725

Video Solution

Step-by-Step Solution

We will use the Pythagorean theorem in order to find the side DC:

(BC)2+(DC)2=(DB)2 (BC)^2+(DC)^2=(DB)^2

We begin by inserting the existing data into the theorem:

72+(DC)2=252 7^2+(DC)^2=25^2

49+DC2=625 49+DC^2=625

DC2=62549=576 DC^2=625-49=576

Finally we extract the root:

DC=576=24 DC=\sqrt{576}=24

Answer

168

Exercise #2

The trapezoid ABCD and the rectangle ABGE are shown in the figure below.

Given in cm:

AB = 5

BC = 5

GC = 3

Calculate the area of the rectangle ABGE.

555555333AAABBBCCCDDDEEEGGG

Video Solution

Step-by-Step Solution

Let's calculate side BG using the Pythagorean theorem:

BG2+GC2=BC2 BG^2+GC^2=BC^2

We'll substitute the known data:

BG2+32=52 BG^2+3^2=5^2

BG2+9=25 BG^2+9=25

BG2=16 BG^2=16

BG=16=4 BG=\sqrt{16}=4

Now we can calculate the area of rectangle ABGE since we have the length and width:

5×4=20 5\times4=20

Answer

20

Exercise #3

In a rectangular shopping mall they want to place a deltoid-shaped stage.

The length of the rectangle is 30 meters and the width 20 meters.

What is the area of the orange scenario?

202020303030AAABBBCCCDDD

Video Solution

Step-by-Step Solution

We can calculate the area of rectangle ABCD:

20×30=600 20\times30=600

Let's divide the deltoid along its length and width and add the following points:

202020303030PPPMMMNNNKKKAAABBBCCCDDDNow we can calculate the area of deltoid PMNK:

PMNK=PN×MK2=20×302=6002=300 PMNK=\frac{PN\times MK}{2}=\frac{20\times30}{2}=\frac{600}{2}=300

Answer

300 m

Exercise #4

Given: the length of a rectangle is 3 greater than its width.

The area of the rectangle is equal to 27 cm².

Calculate the length of the rectangle

2727273x3x3xxxx

Video Solution

Step-by-Step Solution

The area of the rectangle is equal to length multiplied by width.

Let's set up the data in the formula:

27=3x×x 27=3x\times x

27=3x2 27=3x^2

273=3x23 \frac{27}{3}=\frac{3x^2}{3}

9=x2 9=x^2

x=9=3 x=\sqrt{9}=3

Answer

x=3 x=3

Exercise #5

The area of the rectangle below is equal to 22x.

Calculate x.

x+8x+8x+8

Video Solution

Step-by-Step Solution

The area of the rectangle is equal to the length multiplied by the width.

Let's list the known data:

22x=12x×(x+8) 22x=\frac{1}{2}x\times(x+8)

22x=12x2+12x8 22x=\frac{1}{2}x^2+\frac{1}{2}x8

22x=12x2+4x 22x=\frac{1}{2}x^2+4x

0=12x2+4x22x 0=\frac{1}{2}x^2+4x-22x

0=12x218x 0=\frac{1}{2}x^2-18x

0=12x(x36) 0=\frac{1}{2}x(x-36)

For the equation to be equal, x needs to be equal to 36

Answer

x=36 x=36

Exercise #6

ABCD is a parallelogram and AEFD is a rectangle.

AE = 7

The area of AEFD is 35 cm².

CF = 2

What is the area of the parallelogram?

S=35S=35S=35777222AAAEEEDDDFFFCCCBBB

Video Solution

Step-by-Step Solution

Let's first calculate the sides of the rectangle:

AEDF=AE×ED AEDF=AE\times ED

Let's input the known data:

35=7×ED 35=7\times ED

Let's divide the two legs by 7:

ED=5 ED=5

Since AEDF is a rectangle, we can claim that:

ED=FD=7

Let's calculate side CD:

2+7=9 2+7=9

Let's calculate the area of parallelogram ABCD:

ABCD=CD×ED ABCD=CD\times ED

Let's input the known data:

ABCD=9×5=45 ABCD=9\times5=45

Answer

45 cm².

Exercise #7

Shown below is the rectangle ABCD.

Given in cm:

AK = 5

DK = 4

The area of the rectangle is 24 cm².

Calculate the side AB.

S=24S=24S=24555444AAABBBCCCDDDKKK

Video Solution

Step-by-Step Solution

Let's look at triangle ADK to calculate side AD:

AD2+DK2=AK2 AD^2+DK^2=AK^2

Let's input the given data:

AD2+42=52 AD^2+4^2=5^2

AD2+16=25 AD^2+16=25

We'll move 16 to the other side and change the appropriate sign:

AD2=2516 AD^2=25-16

AD2=9 AD^2=9

We'll take the square root and get:

AD=3 AD=3

Since AD is a side of rectangle ABCD, we can calculate side AB as follows:

S=AB×AD S=AB\times AD

Let's input the given data:

24=3×AB 24=3\times AB

We'll divide both sides by 3:

AB=8 AB=8

Answer

8

Exercise #8

Given that: the area of the rectangle is equal to 36.

AE=14AB AE=\frac{1}{4}AB

363636333AAABBBDDDCCCEEE

Find the size of AE.

Video Solution

Step-by-Step Solution

The area of rectangle ABCD equals length multiplied by width.

Let's input the known data into the formula in order to find side AB:

36=3×AB 36=3\times AB

Let's divide both sides by 3:

AB=12 AB=12

Since we are given that AE equals a quarter of AB, we can substitute the known data and calculate side AE:

AE=14AB=14×12=3 AE=\frac{1}{4}AB=\frac{1}{4}\times12=3

Answer

3

Exercise #9

The area of the rectangle is equal to 70.

EB=15AB EB=\frac{1}{5}AB

AAABBBDDDCCCEEE707

Calculate the length of EB.

Video Solution

Step-by-Step Solution

The area of rectangle ABCD equals length multiplied by width.

Let's use the known data in the formula to find side AB:

70=7×AB 70=7\times AB

Let's divide both sides by 7:

AB=10 AB=10

Since we are given that EB equals one-fifth of AB, we can use the known data and calculate side EB:

EB=15AB=15×10=2 EB=\frac{1}{5}AB=\frac{1}{5}\times10=2

Answer

2

Exercise #10

Given the rectangle ABCD

Given BC=X and the side AB is larger by 4 cm than the side BC.

The area of the triangle ABC is 8X cm².

What is the area of the rectangle?

S=8XS=8XS=8XX+4X+4X+4XXXAAABBBCCCDDD

Video Solution

Step-by-Step Solution

Let's calculate the area of triangle ABC:

8x=(x+4)x2 8x=\frac{(x+4)x}{2}

Multiply by 2:

16x=(x+4)x 16x=(x+4)x

Divide by x:

16=x+4 16=x+4

Let's move 4 to the left side and change the sign accordingly:

164=x 16-4=x

12=x 12=x

Now let's calculate the area of the rectangle, multiply the length and width where BC equals 12 and AB equals 16:

16×12=192 16\times12=192

Answer

192

Exercise #11

Calculate the area of the rectangle below in terms of a and b.

a+3a+3a+3b+8b+8b+8

Video Solution

Step-by-Step Solution

Let us begin by reminding ourselves of the formula to calculate the area of a rectangle: width X length

S=wh S=w⋅h

When:

S = area

w = width

h = height

We take data from the sides of the rectangle in the figure.w=b+8 w=b+8 h=a+3 h=a+3

We then substitute the above data into the formula in order to calculate the area of the rectangle:

S=wh=(b+8)(a+3) S=w⋅h = (b+8)(a+3)

We use the formula of the extended distributive property:

(a+b)(c+d)=ac+ad+bc+bd (a+b)(c+d)=ac+ad+bc+bd

We substitute once more and solve the problem as follows:

S=(b+8)(a+3)=(b)(a)+(b)(3)+(8)(a)+(8)(3) S=(b+8)(a+3)=(b)(a)+(b)(3)+(8)(a)+(8)(3)

(b)(a)+(b)(3)+(8)(a)+(8)(3)=ab+3b+8a+24 (b)(a)+(b)(3)+(8)(a)+(8)(3)=ab+3b+8a+24

Therefore, the correct answer is option B: ab+8a+3b+24.

Keep in mind that, since there are only addition operations, the order of the terms in the expression can be changed and, therefore,

ab+3b+8a+24=ab+8a+3b+24 ab+3b+8a+24=ab+8a+3b+24

Answer

ab + 8a + 3b + 24

Exercise #12

Express the area of the rectangle below in terms of y and z.

3y3y3yy+3z

Video Solution

Step-by-Step Solution

Let us begin by reminding ourselves of the formula to calculate the area of a rectangle: width X height

S=wh S=w⋅h

Where:

S = area

w = width

h = height

We must first extract the data from the sides of the rectangle shown in the figure.

w=3y w=3y h=y+3z h=y+3z

We then insert the known data into the formula in order to calculate the area of the rectangle:

S=wh=(y+3z)(3y) S=w⋅h=(y+3z)(3y)

We use the distributive property formula:

a(b+c)=ab+ac a\left(b+c\right)=ab+ac

We substitute all known data and solve as follows:

S=(y+3z)(3y)=(3y)(y+3z) S=(y+3z)(3y)=(3y)(y+3z)

(3y)(y+3z)=(3y)(y)+(3y)(3z) (3y)(y+3z)=(3y)(y)+(3y)(3z)

(3y)(y)+(3y)(3z)=3y2+9yz (3y)(y)+(3y)(3z)=3y^2+9yz

Keep in mind that because there is a multiplication operation, the order of the terms in the expression can be changed, hence:

(y+3z)(3y)=(3y)(y+3z) (y+3z)(3y)=(3y)(y+3z)

Therefore, the correct answer is option D: 3y2+9yz 3y^2+9yz

Answer

3y2+9yz 3y^2+9yz

Exercise #13

The area of the rectangle in the drawing is 28X cm².

What is the area of the circle?

S=28XS=28XS=28X777

Video Solution

Step-by-Step Solution

Let's draw the center of the circle and we can divide the diameter of the circle into two equal radii

Now let's calculate the length of the radii as follows:

7×2r=28x 7\times2r=28x

14r=28x 14r=28x

We'll divide both sides by 14:

r=2814x r=\frac{28}{14}x

r=2x r=2x

Let's calculate the circumference of the circle:

P=2π×r=2π×2x=4πx P=2\pi\times r=2\pi\times2x=4\pi x

Answer

4πx 4\pi x

Exercise #14

Calculate the area of the rectangle

y+2y+2y+2x+5x+5x+5

Video Solution

Step-by-Step Solution

Let's begin by reminding ourselves of the formula to calculate the area of a rectangle: width X length

S=wh S=w⋅h

Where:

S = area

w = width

h = height

We extract the data from the sides of the rectangle in the figure.

w=x+5 w=x+5 h=y+2 h=y+2

We then substitute the above data into the formula in order to calculate the area of the rectangle:

S=wh=(x+5)(y+2) S=w⋅h=(x+5)(y+2)

We use the formula of the extended distributive property:

(a+b)(c+d)=ac+ad+bc+bd (a+b)(c+d)=ac+ad+bc+bd

We once again substitute and solve the problem as follows:

S=(x+5)(y+2)=(x)(y)+(x)(2)+(5)(y)+(5)(2) S=(x+5)(y+2)=(x)(y)+(x)(2)+(5)(y)+(5)(2)

(x)(y)+(x)(2)+(5)(y)+(5)(2)=xy+2x+5y+10 (x)(y)+(x)(2)+(5)(y)+(5)(2)=xy+2x+5y+10

Therefore, the correct answer is option C: xy+2x+5y+10.

Answer

xy+2x+5y+10 xy+2x+5y+10

Exercise #15

Below is a hexagon that contains a rectangle inside it.
The area of the rectangle is 28 cm².

777

What is the area of the hexagon?

Video Solution

Step-by-Step Solution

Since we are given the area of the rectangle, let's find the length of the missing side:

7×a=28 7\times a=28

We'll divide both sides by 7 and get:

a=4 a=4

Since in a hexagon all sides are equal to each other, each side is equal to 4.

Now let's calculate the area of the hexagon:

6×a2×34 \frac{6\times a^2\times\sqrt{3}}{4}

6×42×34 \frac{6\times4^2\times\sqrt{3}}{4}

Let's simplify the exponent in the denominator of the fraction and we'll get:

6×4×3=24×3=41.56 6\times4\times\sqrt{3}=24\times\sqrt{3}=41.56

Answer

41.56

Exercise #16

Given the rectangle ABCD

AB=X

The ratio between AB and BC is x2 \sqrt{\frac{x}{2}}

We mark the length of the diagonal A the rectangle in m

Check the correct argument:

XXXmmmAAABBBCCCDDD

Video Solution

Step-by-Step Solution

Given that:

ABBC=x2 \frac{AB}{BC}=\sqrt{\frac{x}{2}}

Given that AB equals X

We will substitute accordingly in the formula:

xBC=x2 \frac{x}{BC}=\frac{\sqrt{x}}{\sqrt{2}}

x2=BCx x\sqrt{2}=BC\sqrt{x}

x2x=BC \frac{x\sqrt{2}}{\sqrt{x}}=BC

x×x×2x=BC \frac{\sqrt{x}\times\sqrt{x}\times\sqrt{2}}{\sqrt{x}}=BC

x×2=BC \sqrt{x}\times\sqrt{2}=BC

Now let's focus on triangle ABC and use the Pythagorean theorem:

AB2+BC2=AC2 AB^2+BC^2=AC^2

Let's substitute the known values:

x2+(x×2)2=m2 x^2+(\sqrt{x}\times\sqrt{2})^2=m^2

x2+x×2=m2 x^2+x\times2=m^2

We'll add 1 to both sides:

x2+2x+1=m2+1 x^2+2x+1=m^2+1

(x+1)2=m2+1 (x+1)^2=m^2+1

Answer

m2+1=(x+1)2 m^2+1=(x+1)^2

Exercise #17

Given the rectangle ABCD

AB=X the ratio between AB and BC is equal tox2 \sqrt{\frac{x}{2}}

We mark the length of the diagonal A A with m m

Check the correct argument:

XXXmmmAAABBBCCCDDD

Video Solution

Step-by-Step Solution

Let's find side BC

Based on what we're given:

ABBC=xBC=x2 \frac{AB}{BC}=\frac{x}{BC}=\sqrt{\frac{x}{2}}

xBC=x2 \frac{x}{BC}=\frac{\sqrt{x}}{\sqrt{2}}

2x=xBC \sqrt{2}x=\sqrt{x}BC

Let's divide by square root x:

2×xx=BC \frac{\sqrt{2}\times x}{\sqrt{x}}=BC

2×x×xx=BC \frac{\sqrt{2}\times\sqrt{x}\times\sqrt{x}}{\sqrt{x}}=BC

Let's reduce the numerator and denominator by square root x:

2x=BC \sqrt{2}\sqrt{x}=BC

We'll use the Pythagorean theorem to calculate the area of triangle ABC:

AB2+BC2=AC2 AB^2+BC^2=AC^2

Let's substitute what we're given:

x2+(2x)2=m2 x^2+(\sqrt{2}\sqrt{x})^2=m^2

x2+2x=m2 x^2+2x=m^2

Answer

x2+2x=m2 x^2+2x=m^2

Exercise #18

The area of the rectangle below is equal to 45.

ED=13AB ED=\frac{1}{3}AB

454545555AAABBBDDDCCCEEE

Calculate the size of ED.

Video Solution

Answer

3

Exercise #19

The perimeter of a rectangle is 14 cm.

The area of the rectangle is 12 cm².

What are the lengths of its sides?

Video Solution

Answer

3, 4

Exercise #20

The height of the house in the drawing is 12x+9 12x+9

its width x+2y x+2y

Given the ceiling height is half the height of the square section.

Express the area of the house shape in the drawing band x and and.

Video Solution

Answer

3x2+8xy+112x+4y2+3y 3x^2+8xy+1\frac{1}{2}x+4y^2+3y