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

hi zee-f

120 is correct for the area.

b= 3√15 / 2 is also correct for the height of the triangle.

Now you can do half base x height to get the area of the triangle and then multiply by the length of the prism.

Bob

#12-
4²+3²=c²
16+9=25
√25=5

5*2+6=16
16*8=128

So #12- D

#13- Longest side is 6 So 6*8= 48

So I got the 8 by multiplying 4 *2 right?

Thank you!! )