SOLUTION: What is the value of sin α if tan α = -5/9 and sec α > 0?

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Question 979151: What is the value of sin α if tan α = -5/9 and sec α > 0?

Answer by jim_thompson5910(35256)   (Show Source): You can put this solution on YOUR website!
Since tangent is negative and secant is positive, this forces the angle to be in quadrant 4.

Draw a right triangle in this quadrant. Make the opposite leg (from the angle) 9 units long. Make the adjacent leg 5 units long. Use the pythagorean theorem to solve to get

So the sine of that angle is

Notes:

1) You can rationalize the denominator, but some books allow you to have that result. If you have to rationalize the denominator, then you should get

2) Sine is negative in Q4.

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