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12. A propeller rotates 6 times every 15
seconds. Based on this information, which of
the following could NOT be true?
A. The propeller rotates 30 times in 90
seconds.
B. The propeller rotates 24 times in one
minute.
C. The propeller rotates 18 times in 45
seconds.
D. The propeller rotates 12 times in 30
seconds.

A.The propeller rotates 30 times in 90 seconds

Step-by-step explanation:

Is not true as the propeller would rotate 36 times.

the answer is A, 15*6= 90 so 6*6=36 which is not 30

step-by-step explanation:

there is a formula i can give you:

it is r^2*n*sin(360/n) divided by 2 where r represents the "radius" and n is the number of sides.

plug them in:

(10sqrt(3))^2*6*sin(360/6) divided by 2

100*3*6*sin(60) divided by 2

900*sin(60)

900*sqrt(3)/2

450*sqrt(3)

approx is 779.4 cm^2