Jan 26Expression of the form a2-b2*x2 : We make a sine substitutionSubstitute x=a/b*sin(θ) (-π/2≤θ≤π/2) so d(x)=a/b*cos(θ)*d(θ) and then √(,a2-b2*x2)=√(,a2-b2*(a/b*sin(θ))2)=√(,a2-a2*sin2(θ))=a√(,1-sin2(θ)) =a√(,cos2(θ))=a*cos(θ)