Question

Let sin p = .71. Which of the following is cos(2p)?
A. –.0082
B. .082
C. –.82
D. .0082

Answer 1

Hint: cos(2p) = 1 - (sin(p))^2

Answer 2

\[\bf \cos(2x)=1-2\sin^2(x)\]

Answer 3

@jim_thompson5910 WE THINK ALIKE.

Answer 4

oh right, there's a 2

Answer 5

Hint: cos(2p) = 1 - 2*(sin(p))^2

almost alike lol

Answer 6

this identity (along with others) was found here: http://www.sosmath.com/trig/Trig5/trig5/trig5.html

Answer 7

@jim_thompson5910 I must congratulate you on your brave efforts.

Answer 8

thanks

Answer 9

I got 1.50, which clearly isn't an available answer. @jim_thompson5910 @genius12

Answer 10

you typed it in wrong

Answer 11

cos(2p) = 1 - 2*(sin(p))^2

cos(2p) = 1 - 2*(0.71)^2

cos(2p) = ???

Answer 12

A :) @jim_thompson5910

Answer 13

correct