Question

A right-angled triangle DEF is placed on top of a

rectangle DFGH to form a compound shape.
What is the perimeter of this shape?
Give your answer in centimetres (cm) to 1 d.p.
3 cm
D
H
5 cm
E
6 cm
F
3 cm

Answer 1

24.8cm

Explanation:

To find the perimeter of the compound shape we first jave to find distance DE. For this we can use pythagoras theorem which states that the square of the longest side of a RIGHT-ANGLED TRIANGLE (which is opposite the right angle) is equal to the sum of the squares of the two adjuscent sides.

USING TRIANGLE EFD

ED² = EF²+FD² (Pythagoras theorem)

ED² = 6²+5²

ED²=61

find the square root of both sides to find distance ED

`\sqrt{ {ed}^(2) } = √(61)`

ED= 7.8 cm

Add up all the distances on the exterior edges of the shape to find the perimeter.

6cm+3cm+5cm+3cm+7.8cm=24.8cm