Question

Which of the following are trigonometric identities?

A. cos22x + sin22x = 1
B. sec2x + csc2x = 1
C. sec2x - tan2x = 1
D. tan2x - sec2x = 1

Answer 1

for A do you mean
cos^2 (2x) + sin^2 (2x) = 1 ?

(the 22x is confusing)

if so, there is an identity: sin^2(A)+ cos^2(A) = 1
which is true for any A (including A=2x)

Answer 2

Which of the following pairs of coordinates do not represent the same point in polar coordinates?

A. (r,θ) and (-r,θ)
B. (r,θ) and (-r,θ +π )
C. (r,θ) and (-r,θ + 2π)
D. (r,θ) and (r,θ + 2π)

Answer 3

any ideas ?

Answer 4

Sorry the answers for the first on are\[A. \cos^22x+\sin^22x=1\]\[B. \sec^2x+\csc^2x=1\]\[C. \sec^2x-\tan^2x=1\]\[D. \tan^2x-\sec^2x=1\]

Answer 5

@phi