Question

A rectangle has a diagonal of 15cm and a width of 9cm. Find its length. Hint: draw a rectangle and divide in half using a diagonal!

Answer 1

12

Explanation:

Imagine a rectangle cut in half along a diagonal. This makes a right angled triangle. This means we can use pythagoras' theorem of a^2+b^2=c^2

For length x we have x^2 + 9^2 = 15^2 so x^2 + 81 = 225

x^2 = 225 - 81 = 144 so x = √144 = 12

Answer 2

Answer: The rectangle has a length of 12 cm.

Steps: I found this using the Pythagorean theorem. (a^2 + b^2= c^2) I made b=9 and c=15. And solved the equation for a.