SOLUTION: given ∆ABC is isosceles with angleB = angleC, show that 2cotA = tanB - cotB

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Question 1003700: given ∆ABC is isosceles with angleB = angleC, show that 2cotA = tanB - cotB
Answer by Edwin McCravy(20060)   (Show Source): You can put this solution on YOUR website!


We work with the left side.

given isosceles triangle ABC, with B = C we have:

A+B+C = 180°
A+B+B = 180°
A+2B = 180°
A = 180° - 2B
cot(A) = cot(180°-2B) = -cot(2B)

So the left side

  becomes























Edwin
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