Law of cosines and trig complex numbers

a^2 =

b^2 + c^2 - 2bc cos A

b^2 =

a^2 + c^2 - 2ac cos B

c^2 =

a^2 + b^2 - 2ab cos C

r1 (cosx1 + i sinx1) \* r2(cosx2 + i sinx2)

r1 r2 \[cos(x1 + x2) + i sin (x1 + x2)\]

r1 (cos x1 + i sin x1) / r2 (cos x2 + i sin x2)

r1/r2 \[cos (x1 - x2) + i sin (x1 - x2)\]

Area of triangle

1/2 (side 1) \* (side 2) sin angle

how to solve addition of ordinents

1. draw triangle w/ coeff corresponding to sin and cos in sin (a+b)
2. calculate hypotonuse
3. Take out amplitude of sin (a+b) equation
4. calculate values of angles for sin and cos in a+b
5. solve