Trigonometry: Sine and Cosine Laws

What is the sine law formula for a triangle?

• a/b = sin(A) + sin(B) + sin(C)

• a/b = sin(A)/sin(B) = c/sin(C)

• a/b = cos(A)/cos(B) = c/cos(C)

• a/b = tan(A)/tan(B) = c/tan(C)

If a triangle has sides of lengths 7, 8, and 9, use the cosine law to find the angle opposite the side of length 7.

• angle C = cos^(-1)(1/2)

• angle C = cos^(-1)(2/3)

• angle C = cos^(-1)(3/4)

• angle C = cos^(-1)(4/5)

In a triangle, if angle A = 30° and side a = 10, what is the length of side b if angle B = 45°?

• 5√2

• 15

• 10√3

• 10√2

Using the sine law, if angle A = 60° and side a = 12, find side b if angle B = 30°.

• 4√3

• 10

• 8√2

• 6

A triangle has sides of lengths 5, 12, and 13. Verify if it is a right triangle using the cosine law.

• Yes, it is an equilateral triangle.

• No, it is a scalene triangle.

• No, it is an obtuse triangle.

• Yes, it is a right triangle.