Let
y=y1+y2y1=tan−1(4cosx+3sinx3cosx−4sinx)Dividing the numerator and denominator by
4cosx:
y1=tan−11+43tanx43−tanxUsing the formula
tan−1(1+ABA−B)=tan−1A−tan−1B:
y1=tan−1(43)−tan−1(tanx)=tan−1(43)−xDifferentiating with respect to
x:
dxdy1=−1Now,
y2=2tan−1(1+1−x2x)Substituting
x=sinθ:
y2=2tan−1(1+cosθsinθ)y2=2tan−1(2cos2(θ/2)2sin(θ/2)cos(θ/2))y2=2tan−1(tan2θ)=2(2θ)=θ=sin−1xDifferentiating with respect to
x:
dxdy2=1−x21At
x=23:
dxdy2=1−(23)21=1−431=411=2Therefore,
dxdy=dxdy1+dxdy2=−1+2=1Answer:
1