How many solutions exist for the equation cos 2θ − sin θ = 0 on the interval [0, 360°)?
1 answer:
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Answer:
a. 11/5 pi; -9/5 pi
Step-by-step explanation:
Coterminal angles are those which have a common terminal side. For example 30° is coterminal with −330° and 390° (see figure).
From the example we can see that the following expressions must be fulfilled:
positive angle - reference angle = 360°
reference angle - negative angle = 360°
where positive angle is 390°, reference angle is 30° and negative angle is -330°. In this problem reference angle is pi/5. Also, we have to change 360° for its equivalent in radians, i. e., 2 pi. So,
positive angle - pi/5 = 2 pi
positive angle = 2 pi + pi/5
positive angle = 11/5 pi
pi/5 - negative angle = 2 pi
negative angle = pi/5 - 2 pi
negative angle = -9/5 pi
