1.3

Question 0

angle addition formulas

Answer 0

sin(A+B)=sinAcosB+sinBcosA

cos(A+B)=cosAcosB-sinAsinB

Question 1

Pythagorean identities

Answer 1

cos^2θ + sin^2θ = 1
1 + tan^2θ = sec^2θ
1 + cot^2θ = csc^2θ

Question 2

double angle formulas

Answer 2

cos2θ = cos^2θ - sin^2θ
sin2θ = 2sinθcosθ

Question 3

half angle formulas

Answer 3

sin^2θ = (1 - cos 2θ)/2
cos^2θ = (1 + cos 2θ)/2

Question 4

law of cosines

Answer 4

c^2 = a^2 + b^2 - 2ab cosθ

Question 5

law of sines

Answer 5

(sinA)/a = (sinB)/b = (sinC)/c