(a)Derive geometrically that `cos(x+y)=cos x cos y-sin x sin y`.Hence deduce the valueof `cos 75^@`

Prove geometrically that cos (x+y) =cosx cosy +sin x sin y

Prove geometrically that cos(x + y) = cos x cos y - sinx sin y and hence prove cos((pi)/(2) + x) = - sin x .

Prove Geometrically cos(x+y)=cosx,cosy-sinx.siny and hence prove that cos(x-y)= cosxcosy+sinxsiny using unit circle concept ?

To cos(A+B)=cosx.cosy - sin x sin "and hence find "cos75^(@)

If sin x+sin y=3(cos y-cos x) then the value of sin 3 x+sin 3 y=

If y = cos(log sin x), then dy/dx =

The maximum value of y=a cos x + b sin x is