Question

Which of the following equations are identities. Check all that apply

A) cotx= cosx/sinx
B) cscx=1/cosx
C) tanx=1/cotx
D) cscx=1/secx

Answer 1

A) cotx = cosx/sinx

C) tanx = 1/cotx

Explanation:

A)

cosx/sinx = 1/(sinx/cosx) = 1/tanx = cotx

Therefore, cotx = cosx/sinx

C)

Similarly;

1/tanx = cotx

Therefore,

1 = tanxcotx

1/cotx = tanx

and

tanx = 1/cotx

B) cscx=1/cosx is not true since;

1/cosx = secx

and

cscx = 1/sinx