यदि `tan^(4)theta+tan^(2)theta=1` हो, तो `cos^(4)theta+cos^(2)theta` का मान क्या होगा ?

Options

A. 2
B. 0
C. 1
D. -1

Answer

c

Explanation

`tan^(4)theta+tan^(2)theta=1`
`because sec^(2)tyheta-tan^(2)theta=1`
`tan^(@)(1+tan^(2)theta)=1`
` tan^(2)theta (sec^(2)theta)=1`
`tan^(2)theta=(1)/(sec^(2)theta)`
`tan^(2)theta=cos^(2)theta`
`because cos^(4)theta+cos^(4)theta`
`=(cos^(2)theta)^(2)+cos^(2)theta`
`=(tan^(2)theta)+tan^(2)theta`
=1 frame equation (i)