Question

Find the Surface Area of : [2 MARKS]

Answer 1

Concept: 1 Mark
Application: 1 Mark

Surface area = area of 5 surfaces of prism + area 4 triangles

We need to know the height of each triangle, so we calculate it by the theorem of Pythagoras.

So in the triangle $S^2={20}^2+{15}^2$

$S^2=400+225$

$S^2=625$

$S=25cm$

So surface area becomes
$=(30\times 30)+4(30\times 15)+4(\frac{1}{2}\times 30\times 25)$

$=900+1800+1500$

$=4200c{m}^2$