Download Trigonometry Section 7.3 Define the sine and cosine functions

Trigonometry Section 7.3
Define the sine and cosine functions
Sine Θ = y/r
(sin Θ = y/r)
Cosine Θ = x/r (cos Θ = x/r)
Note: The value of the sine and cosine functions depend upon
the quadrant in which the terminal rays of the angle falls.
Sign of the trigonometric functions
Quadrant 1
sine
cosine
Quadrant 2
Quadrant 3
Quadrant 4
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 3rd quadrant angle and cos Θ = -5/13, find
sin Θ.
The circle x2 + y2 = 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 90o
cos π
sin 450o
cos –π/2
Solve for all values of θ
sin θ = 1
cos θ = 0
sin θ = -1
Order the expressions
sin 40o
sin 50o
cos 40o
cos 50o
sin 10o
sin 170o
cos 10o
cos 170o
assignment
• Page 272
• Problems 1 – 28, 34-40 not ÷3