Question

Question #0afb5

Answer 1

Reqd. Value `=0.`

Explanation:

We have the Formula `:costheta=sin(90^@-theta) rArr cos20^@=sin70^@`

Hence, the Exp.`=1-cos^2(20^@)-cos^2(70^@)`
`=1-sin^2(70^@)-cos^2(70^@)`
`=1-{sin^2(70^@)+cos^2(70^@)}`
`+1-1=0.`