SOLUTION: Consider an isosceles triangle ABC with lengths of AB=AC=1 and angle BAC =36 degrees. Find the length of BC. Hint: construct angle bisector of angle ABC>
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Question 15373: Consider an isosceles triangle ABC with lengths of AB=AC=1 and angle BAC =36 degrees. Find the length of BC. Hint: construct angle bisector of angle ABC> Answer by rapaljer(4671) (Show Source):
You can put this solution on YOUR website! The angle bisector of angle BAC is perpendicular to side BC, so it forms a right triangle with angle at point A of 18 degrees, and hypotenuse AB=1. Therefore,
sin 18 = , where x = half of the side BC.
Be sure your calculator is in degree mode and calculate sin 18 = .3090.
Double this value to obtain BC = .618 approximately.
