SSC CHSL 2020 PYQ — Question 64

sec²x = 1 + tan²x

tanx= sinx/cosx

sin²x + cos²x = 1

tan⁴x – tan²x = 1

tan⁴x = 1 + tan²x 

As we know sec²x = 1 + tan²x

So, tan⁴x = sec²x

sin⁴x/cos⁴x = 1/cos²x

sin⁴x = cos²x   ..... (i)

We need to find the value of 

Sin⁴x + Sin²x.

We can put the value of Sin⁴x from equation (i).

 cos²x  + Sin²x

And the value of cos²x  + Sin²x is equal to 1.