So the best and correct answer is C because this is how you do it The surface area of the cone has formula
pi * radius * ( radius + sqrt ( height^2 + radius^2)) =
pi * radius^2 + pi * radius * sqrt( height^2 + radius^2)
However, this includes the base of the cone and the hats do NOT have
that. "The hats are shaped like a cone with NO BASE", says the 3rd sentence.
So the formula becomes pi * radius * sqrt( height^2 + radius^2)
diameter = 16
radius = 8
height = 9
The surface area of ONE of the hats is pi * 8 * sqrt( 9^2 + 8^2)
= pi * 8 * sqrt( 81+64)
= pi * 8 * sqrt(145)
302.63828053.....
21 of them is 21 * 302... = 6355.40689112841343251026086.....
Answer: 12πins.
Step-by-step explanation:
Since the area if a circle = πr²
From the question
Area of the circle = 36πins²
To find the circumference of the circle, we need to find the common radius of the circle and this could be achieved from the area of the circle given above.
πr² = 36π, solving this gives. Divide through by π
r² = 36
r = +/-√36
= +/-6
Now to find the circumference of the circle, we substitute for r in the formula below.
Circumstances = 2πr
= 2 ×π × 6
= 12πins.
1 3 1×3 3
--- × --- = ------ = ----
2 4 2×4 8
5 5 5×5 25
--- × ---- = --------- = -------
6 7 6×7 42
hope is understandably
