SmarterEd

Aussie Maths & Science Teachers: Save your time with SmarterEd

Area, SM-Bank 011

This triangle was made by cutting a square in half.
 

 
The perimeter of the triangle is 51.21 cm.

What is the area of the triangle?  (2 marks)

Show Answers Only

\(112.5\ \text{cm}^2\)

Show Worked Solution

\(\text{Triangle is isosceles with perimeter}=51.21\ \text{cm.}\)

\(\Rightarrow\ \text{Length of triangle side}\)

\(=\dfrac{1}{2}\times (51.21 – 21.21)\)

\(=\dfrac{1}{2}\times 30\)

\(=15\ \text{cm}\)

\(\therefore\ \text{Area}\) \(=\dfrac{1}{2}\times bh\)
  \(=\dfrac{1}{2}\times 15\times 15\)
  \(=112.5\ \text{cm}^2\)