Question

If `cos theta =7/8,`evaluate`{(1+sin theta)(1-sin theta)]/[(1+cos theta)(1-cos theta)]`?

Answer 1

`{(1+sin theta)(1-sin theta)]/[(1+cos theta)(1-cos theta)]`

`=(1-sin^2theta)/(1-cos^2theta)`

`=(cos^2theta)/(1-cos^2theta)`

`=(7/8)^2/(1-(7/8)^2)`

`=(7/8)^2/((8^2-7^2)/8^2)`

`=49/15`