Use Heron's Formula:
s means semi-perimeter = (50 + 31 + 18) / 2 = 99 / 2 =
49.5
area = sq root [(s * (s-a) * (s-b) * (s-c)]
area = sq root [(49.5 * (s-a) * (s-b) * (s-c)]
This will NOT form a triangle. The longest side (50) is greater than the sum of the other 2 sides.
Source:
http://www.1728.org/trianinq.htm
The answer is (c) (sorry adding extra characters so brainly can exept it.)
X + 2x + x + 10 = 90
4x = 80
x = 20
The area of a circle is:

"r" being the radius and π being 3.14
14. The diameter is 12. So, to get the radius, we would need to halve it. So, the radius would be 6.
Now we plug in 6 for r and 3.14 for π which makes it

which equals 113.04
15. The diameter is 9, so to get the radius we need to halve it to get 4.5
Plug in 4.5 for r and 3.14 for π and we get

which equals 63.585
16. The diameter is 18, so to get the radius we need to halve it to get 9
Plug in 9 for r and 3.14 for π and we get

which equals 254.34
17. The diameter is 8, so to get the radius we need to halve it to get 4.
Plug in 4 for r and 3.14 for π and we get