Question

Question #3acab

Answer 1

`"see explanation"`

Explanation:

`"using right triangle with a vertex at the origin and angle "`
`theta," with sides corresponding to " theta`

`"adjacent "=x ," opposite " =y ," hypotenuse " =r`

`rArrsintheta=y/r , costheta=x/r" and " r^2=x^2+y^2`

`rArr1-sin^2theta=1-y^2/(r^2)=r^2/(r^2)-y^2/(r^2)`

`rArr1-sin^2theta=(r^2-y^2)/r^2=x^2/(r^2)=cos^2theta`