Question

Prove the cofunction identity using the addition and subtraction formula? sec(pi/2-u)=csc u

Answer 1

See below...

Explanation:

Using the identities:
`secu= 1/cosu`

`1/sinu= cscu`

`cos(a-b)= cosacosb+sinasinb`

Start:

`sec(pi/2-u)=csc u`

`1/(cos(pi/2-u))= cscu`

`1/(cos(pi/2)*cosu+sin(pi/2)*sinu)`

`1/(cancel((0)*cosu)+(1)*sinu)`

`1/sinu= cscu`

`cscu=cscu`