How do you solve cost-sin(2t)=0?

1 Answer
Nghi N.
Oct 18, 2016

pi/6, pi/2, (5pi)/6, (3pi)/2

Explanation:

Use trig identity:
sin 2t = 2sint.cos t
f(t) = cos t - 2sin t.cos t = cos t(1 - 2sin t) = 0
Use trig table and unit circle:
a. cos t = 0 --> arc t = pi/2 and arc t = (3pi)/2
b. (1 - 2sin t) = 0
sin t = 1/2
Trig table and unit circle -->
arc t = pi/6 and arc t = pi - pi/6 = (5pi)/6
Answers for (0, 2pi):
pi/6; pi/2, (5pi)/6, (3pi)/2

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