In triangle ABC, a = 9, c = 5, and angle B = 120°. Find the measure of angle A to the nearest degree. Show your work.

Question

Mathematics

Aliana Diaz

24 February, 11:48

In triangle ABC, a = 9, c = 5, and angle B = 120°. Find the measure of angle A to the nearest degree. Show your work.

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Answers (1)

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Vinnie · Answer 1

We can use the cosine law and the sine law in order to solve angle A. The cosine law is used when we are finding the third side and we are given two sides of a triangle and the angle between the sides. It is expressed as:

a^2 = b^2 + c^2 - 2bc cos A

The sine law is an equation which relates the length of any sides of the triangle to the sine of the angles of the triangle. It is expressed as:

a/sinA = b/sinB = c/sinC

Usin the two equations, yields to a value of Angle A which is 39.37 degrees.