Question

How do you find exact value with out calculator `1-tan^2 10+ csc^2 80`?

Answer 1

Try this method

`t = 1-tan^2(10^0)+csc^2(80^0)`
`= 1-tan^2(10^0)+csc(90^0-10^0)^2`
`=1-tan^2(10^0)+sec^2(10^0)`
`=1+(1-sin^2(10^0))/cos^2(10^0)`
`=1+1`
`=2`