Question

Which of the following is an identity?

A: secBcotB = cosB
B: secBcotB = cscB
C: secBcotB = sinB
D: secBcotB = cscBtanB

Answer 1

The answer is option B

Explanation:

secB = 1/cosB

cotB = cosB / sinB

secBcotB is

`(1)/( \cos(B) ) * ( \cos(B) )/( \sin(B) ) \\ \\ = (1)/( \sin(B) ) \\ \\ But \: (1)/( \sin(B) ) = \csc(B) \\ \\ \\ = \csc(B)`

Hence the identity

Hope this helps you