Lily Quinn makes $12.50 and hour. She works four hours on Monday, six hours on Tuesday, nine hours on Wednesday, three hours on
Thursday, and seven hours on Friday. What is her gross pay? A. $420.50 B. $325.50 C. $362.50 D. $462.50
1 answer:
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Answer:
x ∈ {2π/3, π, 4π/3} ≈ {2.09440, 3.14159, 4.18879}
Step-by-step explanation:
The equation can be put into standard form by adding 1:
2cos²(x) +3cos(x) +1 = 0
(2cos(x) +1)(cos(x) +1) = 0
Values of cos(x) that make this true* are ...
cos(x) = -1/2 . . . . . . . . . true for x=2π/3, x=4π/3
cos(x) = -1 . . . . . . . . . . . true for x=π
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A graphing calculator can be helpful here, too.
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* from your knowledge of the short table of trig functions and their signs in different quadrants
