Post

@MathMath901 ∫ sin θ d(cos θ)
= ∫ (sin θ. (–sin θ dθ))
= ∫ (–sin² θ. dθ)
= ∫ (–½ (1 – cos 2θ)) dθ
= ∫ (–½ dθ) + ∫ (½ cos 2θ dθ)
= –½ θ + ½. ½ sin 2θ + C
= –½ θ + ¼ sin 2θ + C
Suomi

@MathMath901 1. intergrate sin (theta) d(cos(theta))
start with d cos theta = - sin theta d theta
and intergrate sin = sin^squared theta add 1 to the power divide by the old power sin^2/1 = sin^2
--
the solution for first intergral is this:
sin^2(theta) * - sin(d (theta))
English

@MathMath901 acknowlegde the problem here are my steps:
lookup table deriavation table :
1. sin -> 2. cos ->3. -sin -> 4. -cos
rewrite the indefinite intergral step
deriavation -1 from the power then mutiply by the old power
intergration +1 to the power divide by the new power
English

@MathMath901 now for the third:
1/2 sin(theta) ^3 - cos(theta) +C
= (sin(theta) ^ 3*1/2 = 1/2*3 =1/4 * 1/2 = 1/8 * - (-sin(theta))
English

@MathMath901 Hmmm ... isn't d(cos(\theta)) = -sin(\theta) d(\theta).
English

@MathMath901 now the double intergral sin^2 * -sin(d(theta))
----
sin^3/2 = 1/2 sin(sin^3)* - cos(theta) + C
English

