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The terminal ray of angle  β , drawn in standard position, passes through the point (−4, 3√5) .

What is the value of cosβ ?

Give your answer in simplest radical form

 Mar 10, 2020
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"The terminal ray of angle  β , drawn in standard position, passes through the point (−4, 3√5) .

What is the value of cosβ ?"

 

This puts the angle in the second quadrant so cosβ will be negative.

 

Imagine a right angled triangle where the hypotenuse reaches from the origin to the point. 

Then the length of the hypotenuse is given by sqrt((-4)2 + (3√5)2) = √61

 

Hence cosβ = -4/√61  or  cosβ = -4√61/61

 Mar 10, 2020

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