Question

in triangle ABC, prove that cos (a+b) + cos c =0​

Answer 1

Answer:

Step-by-step explanation:

A+B+C=π(three angle sum of triangle is 180°)

Cos(π-C)+cosC

=-CosC+CosC=0(2nd quadrant cos value negative)

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Answer 2

Answer:

Step-by-step explanation:

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