Question

Which of the following statements is not true? *

tan θ = cot (90 – θ)
sin θ = cos (90 – θ)
sec A = cos (90 – A)
sin 90 = 1 / cosec 90​

Answer 1

Answer:

sec A = cos(90-A) is wrong.

Step-by-step explanation:

We all know,

For complementary angles,

$\sin(90 - \alpha ) = \cos( \alpha ) \: and \: vice \: versa \\ \sec(90 - \alpha ) = \csc( \alpha ) \: and \: vice \: versa \\ \tan(90 - \alpha ) = \cot( \alpha ) \: and \: vice \: versa$

Also, sin90 = 1/cosec90

Here, In the above statements,

sec A= cos(90-A), which is completely wrong.