January 31, 2017
Precalc Warm Up # 7-2
1. Find the exact value of cos(285°) using a sum formula.
2
2. Solve: 3 tan x + 4 tan x = 4
January 31, 2017
Half Angle Formulas:
The sign depends upon the quadrant in which
u lies. For example, find cos 105 exactly
__
2
(-1,0)
(0,1)
135
150
180
o
o
90
o
60
o
45
o
30
o
o
0
o
210
o
0 or 360
330
o
225
-
120
o
240
o
270
o
300
o
315
o
o
(0,-1)
How else could we have found cos 105° exactly?
o
(1,0)
January 31, 2017
2
Find the general solution to 2-sin x = 2 cos
(0,1)
135
(-1,0)
150
180
o
120
o
90
o
60
45
o
30
o
o
0o
o
0 or 360
330
o
225
315
o
240
o
270
o
x
2
o
o
210
2
300
(1,0)
o
o
o
(0,-1)
x = /2 + n and x = 2 n
January 31, 2017
u ) when cot u = 3,
Find the exact value of sin ( __
2
January 31, 2017
Classwork and Homework