The diagonal of rectangle measures 13cm. The width of the rectangle is 5 cm. Find the length of the rectangle.

diagonal = √(length² + width²)
13 = √(length² + 5²)
13² = length² + 5²
length² = 13²  5² = 169  25 = 144
length = √144 = 12
13 = √(length² + 5²)
13² = length² + 5²
length² = 13²  5² = 169  25 = 144
length = √144 = 12

Use the Pythagorean Theorem ("c" is always the diagonal, or hypotenuse)
a² + b² = c²
5² + b² = 13²
25 + b² = 169
25______25
b² = 144
√b² = √144
b = 12 < This is your answer!
The length of the rectangle is 12 cm.
a² + b² = c²
5² + b² = 13²
25 + b² = 169
25______25
b² = 144
√b² = √144
b = 12 < This is your answer!
The length of the rectangle is 12 cm.