Isosceles 83157

Using the cosine theorem, prove that in an isosceles triangle ABC with base AB, c=2a cos α.

Correct answer:

c = 2a cos α

Step-by-step explanation:

α=β a=b  cos α = c/2 : a  a cos α  = c/2  2a cos α = c  c=2acosα

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Tips for related online calculators
Calculation of an isosceles triangle.
Cosine rule uses trigonometric SAS triangle calculator.
See also our trigonometric triangle calculator.

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