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# Trig

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In triangle ABC, we have angle A = 90 degrees and sin B = (4/7). Find cos C. (No diagram was given)

Sep 11, 2018

#1
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as we know a triangle has 180 degrees we know that angles B and C must sum to 90.

so we have

$$\cos(C) = \cos(90^\circ - B) = \\ \cos(90^\circ)\cos(B) + \sin(90^\circ)\sin(B) = \\ \sin(B) = \dfrac 4 7$$

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Sep 11, 2018