Consider `DeltaACB` , right-angled at C, in which `AB =29` units, `BC =21` units and `/_ABC=theta` . Determine the values of
(i) `cos2theta+sin2theta`
(ii) `cos2thetasin2theta`

Explanation

BY Pythagoras theoram
`AB^2=AC^2+BC^2`
`AC^2=AB^2-BC^2`
`AC^2=29^2-21^2`
`AC=20
UNIT`
`costheta=(BC)/(AB)=21/29`

`sintheta=AC/AB=20/29`
`sin2theta+cos^2theta=(21^2+20^2)/29^2`
`cos^2theta-sin^2theta=(21^2-20^2)/29^2=41/841`