Equilateral Triangle: Solve for X When One Angle is X+5

Below is an equilateral triangle.

Calculate X.

X+5X+5X+5AAABBBCCC

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Step-by-step video solution

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00:00 Determine the value of X
00:03 In an equilateral triangle all angles are equal
00:06 The sum of the angles in a triangle equals 180
00:09 Therefore 3 times the angle equals 180
00:12 Open the brackets and continue to solve
00:16 Isolate X
00:30 This is the solution

Step-by-step written solution

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1

Understand the problem

Below is an equilateral triangle.

Calculate X.

X+5X+5X+5AAABBBCCC

2

Step-by-step solution

Since in an equilateral triangle all sides are equal and all angles are equal. It is also known that in a triangle the sum of angles is 180°, we can calculate X in the following way:

X+5+X+5+X+5=180 X+5+X+5+X+5=180

3X+15=180 3X+15=180

3X=180−15 3X=180-15

3X=165 3X=165

Let's divide both sides by 3:

3X3=1653 \frac{3X}{3}=\frac{165}{3}

X=55 X=55

3

Final Answer

55

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In a right triangle, the side opposite the right angle is called....?

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