8920 so the standard form would be 8.92*10^3
Answer:

Step-by-step explanation:
By the Pythagorean theorem, triangle BCD has

and triangle ABD has
.
Substituting the first equation into the second equation for
gives the equation

Now triangle ABC has

Expanding out the left side,
.
Now substitute the equation from before,
, into the new equation.


We work to isolate
by adding
to both sides of equation and subtracting
from both sides.

Divide both sides by 2 and you get 
Assume that x is positive and square root both sides to get the final result of

Cos(12x) = cos(6x+6x) = cos6xcos6x -sin6xsin6x = cos^2(6x) -sin^2(6x)
1 - cos(12x) = 1 - (cos^2(6x) -sin^2(6x)) = sin^2(6x) +cos^2(6x) - cos^2(6x) +sin^2(6x) = 2sin^2(6x)
so choice A. is right sure
Answer:
i strongly believe the answer is (c)
Step-by-step explanation: