hi zee-f

If you got the rest correct, that was very good, well done.

Now for the corrections:

5.C

5. the base is an isosceles triangle with a height of 8 and a base of 3 (sides of 6)

A Lateral area: 120; Volume: 18*sqrt(15)

BLateral area: 100; Volume: 96

CLateral area: 192; Volume: 144

DLateral area: 176; Volume: 18*sqrt(15)

E Lateral area: 288; Volume: 288

F Lateral area: 240; Volume: 64

I'm thinking this is a prism, that is 8 tall. It has an isosceles trianle for a base, with sides 6, 6 and 3.

So the perimeter is 6 + 6 + 3 = ?

So the lateral area = perimeter x 8.

Now for the volume.

You have to work out the height of the triangle.

I'll use Pythagoras to get it.

Split the triangle in half so that there's a right angle. Hypotenuse = 6 shortest side = 1.5

Then multiply by 8

I got a decimal answer for this, so I had to check what 18 x sqrt(15) comes to.

I have an isosceles triangle with a height of 4 and a base of 6:

11- C (this was correct)

11. What is the area?

A 19

B 35

C 12

D 16

E 22

F 54

This triangle just became the base of a regular prism, with a height of 8:

12-F

12. What is the lateral area?

A 105

B 28

C 35

D 128

E 56

F 12

You need to work out the sides. The base is 6 but what about the two equal sides.

If you split the isosceles triangle down the middle to make a right angle. Half the base is 3 and the height is 4.

Then perimeter is this answer twice plus the base. Then multiply by 8. I can see the answer in the list.

13-C

13. What is the area of the largest rectangular side?

A 95

B 54

C 32

D 48

E 96

F 10

And you can get the largest by taking the longest side and multiplying by 8.

I can see this answer in the list.

Bob