Below is the rectangle ABCD.
It has an area of 42 cm² and side AD is equal to 12 cm.
What is the length of side DC?
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Below is the rectangle ABCD.
It has an area of 42 cm² and side AD is equal to 12 cm.
What is the length of side DC?
Remember that to calculate the area of the rectangle, we multiply the length by the width.
Therefore:
Divide both sides by 12:
3.5
Look at the rectangle below.
Side DC has a length of 1.5 cm and side AD has a length of 9.5 cm.
What is the perimeter of the rectangle?
Because area uses multiplication! The formula A = length × width means 42 = 12 × DC. To solve for DC, we need the opposite operation of multiplication, which is division.
It doesn't matter! In rectangles, you can call either dimension length or width. The area formula works the same way: Area = side₁ × side₂.
Check your work! If one side is large (like 12 cm) and the area is not huge (42 cm²), then the other side should be smaller. That's mathematically correct!
Yes! As long as you know the area and one side length, you can always find the missing side by dividing:
Multiply it back: 3.5 × 12 = 42 cm². Since this matches the given area, 3.5 cm is correct! Always verify by checking that length × width = given area.
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