int sin^4x = a million/4 int (2 sin^2x)^2 dx = a million/4 int [ a million- cos2x]^2 dx =a million/4 int [ a million - 2 cos2x + cos^2 (2x) ] dx = a million/4 x - a million/4 sin2x + a million/4 int [ a million+ cos4x]/2 dx = a million/4x- a million/4sin2x + a million/8 x + a million/32 sin4x + C = 3/8x - a million/4 sin2x + a million/32 sin4x + C
Answers & Comments
Let y=sin^-1 x
siny =x
differentiate both sides with respect to x
cos y dy/dx =1
sqrt(1-sin^2 y) dy/dx=1
sqrt(1-x^2) dy/dx=1
dy/dx = 1/sqrt(1-x^2)
2)
y=sin^-1 x
sin y = x
cos y dy/dx = 1
dy/dx = 1/cos y
Let sin^-1(x) = u
x = sin u......(i)
Differentiate
dx/du = cos(u) = sqrt(1- sin^2(u)) = sqrt(1-x^2) ....(ii)
and y =u
Differentiate
dy/dx = du/dx = 1/cosy .....(ii)
From (i) and(ii)
dy/dx = 1/1/√(1-x^2)
Hence ((d\dx) sin^-1 x) = 1/√(1-x^2) .............Ans
int sin^4x = a million/4 int (2 sin^2x)^2 dx = a million/4 int [ a million- cos2x]^2 dx =a million/4 int [ a million - 2 cos2x + cos^2 (2x) ] dx = a million/4 x - a million/4 sin2x + a million/4 int [ a million+ cos4x]/2 dx = a million/4x- a million/4sin2x + a million/8 x + a million/32 sin4x + C = 3/8x - a million/4 sin2x + a million/32 sin4x + C