Second, cosh-1xdx = xcosh-1x-+C.

Three. TANH- 1x dx = XTANH- 1x+LN | 1-X2 |+c

Four. coth- 1x dx = xcotth- 1x-ln | 1-x2 |+c。

Verb (abbreviation of verb) sech-1xdx = xsech-1x-sin-1x+C.

6.CSCH- 1x dx = XCCH- 1x+SINH- 1x+c

Seven, sin 3θ=3sinθ-4sin3θ

Eight, cos3θ=4cos3θ-3cosθ

Nine, →sin3θ= (3sinθ-sin3θ)

X.→cos3θ= (3cosθ+cos3θ)

Xi。 sin (α β) = sin α cos β cos α sin β。

Twelve, cos (α β) = cos α cos β sin α sin β.

Thirteen. 2 sin α cos β = sin (α+β)+sin (α-β)

Fourteen 2 cos α sin β = sin (α+β)-sin (α-β)

Fifteen. 2 cos α cos β = cos (α-β)+cos (α+β)

Sixteen, 2 sin α sin β = cos (α-β)-cos (α+β)

Seventeen, sin α+sin β = 2 sin (α+β) cos (α-β)

18.sin α-sin β = 2 cos (α+β) sin (α-β)

Nineteen. cos α+cos β = 2 cos (α+β) cos (α-β)

Twenty, cos α-cos β = -2 sin (α+β) sin (α-β)