Day 3 – Sine, Cosine and Tangent of Angles from 0 – 360 (CAST)
CAST Rule
Recall: Standard position
- Tells us the ______________ of each trig ratio in each of the ______
Draw the following angles in standard position:
________________________.
Reference Angles:
The reference angle is the _______________ (less than 90°) angle
Why are Reference Angle Important?
between the terminal arm and the ___________________.
Ex. 2 Find the exact trig ratio of the following:
**
a) sin 135o
Ex. 1 What is the reference angle of the following angles in standard
position?
b) tan( 210o )
c) cos 300
o
d) tan( 150 )
o
Ex. 3: Find the exact values of sin  , cos , and tan  given P(3, -2)
lies on the terminal arm.
b) sin B  
5
, quadrant III
11
4
c) tan C   , quadrant IV
3
12
and angle A is in quadrant I.
13
a) Draw a diagram.
Ex. 5: sin A 
b) Determine exact values of cosA and sinA.
Ex. 4: One of the primary trig ratios is given, as well as the quadrant
in which the terminal arm lies. Determine the other two
primary trig ratios. Give exact answers.
3
a) cos A  , quadrant I
5
c) How would the answers in part a) and b) change if the quadrant of
angle A wasn’t given?