Trigonometry Section 7.3 Define the sine and cosine functions Note: The value of the sine and cosine functions depend upon the quadrant in which the terminal rays of the angle falls. Sine Θ = y/r (sin Θ = y/r) Cosine Θ = x/r (cos Θ = x/r)

Sign of the trigonometric functions Quadrant 1Quadrant 2Quadrant 3Quadrant 4 sine cosine

example If the terminal ray of Θ in standard position passes through (3,-2), find sin Θ and cos Θ.

example If Θ is a 3 rd quadrant angle and cos Θ = -5/13, find sin Θ.

The circle x 2 + y 2 = 1 which has a radius of one and a center at the origin is called the unit circle. sin Θ = y cos Θ = x

example Find the following values. sin 90 o cos π sin 450 o cos –π/2

Solve for all values of θ sin θ = 1 cos θ = 0 sin θ = -1

Order the expressions sin 40 o sin 50 o cos 40 o cos 50 o sin 10 o sin 170 o cos 10 o cos 170 o

assignment Page 272 Problems 1 – 28, not ÷3