Question

If x+12=6cos(theta) for 0 13 years ago

Answer 1

since \(\large x+12=6cos\theta \rightarrow \frac{x+12}{6}=cos\theta \) .
now, the double angle formula states: \(\large cos(2\theta)=cos^2\theta-sin^2\theta \).
\(\large cos^2\theta=\frac{(x+12)^2}{6^2} \)
\(\large sin^2\theta=1-cos^2\theta = 1-\frac{x+12)^2}{6^2}\)

can you take it from here?

Answer 2

ok ill try
thanks much

Answer 3

yw... lemme know if u get stuck.... :)
btw.... that last line should read \(\large sin^2\theta=1-cos^2\theta=1-\frac{(x+12)^2}{6^2}\)

Answer 4

i tried it but my answer in the webwork and it turn out to be wrong........well i actually used the same answer u gave me

Answer 5

this is what i got.... (i skipped some algebra but it's just basically simplification):
\(\large cos2\theta = cos^2\theta - sin^2\theta=\frac{(x+12)^2}{36}-(1-\frac{(x+12)^2}{36})=\frac{x^2}{18}+\frac{4x}{3}+7 \)

Answer 6

ok thanks ill try that