Question

Which of the following are trigonometric identities? (Check all that apply)

a) 1 - tan(x) tan(y) = cos(x+y)/cosx cosy

b) secx - cosx/secx = sin^2 x

c) tan(x)cos(x)csc(x) = 1

d) 4cos(x) sin(x) = 2cos(x) + 1 - 2sin(x)

Answer 1

@KyanTheDoodle @peachpi

Answer 2

@billj5

Answer 3

@perl

Answer 4

@perl

Answer 5

http://www.sosmath.com/trig/Trig5/trig5/trig5.html

Answer 6

i dont understand this @billj5

Answer 7

@perl

Answer 8

@geerky42