Understanding the Sine of 42 Degrees

What is the purpose of using the difference identity for sine in this video?

• To find the exact value of the sine of 42 degrees

• To find the cosine of 42 degrees

• To determine the sine of 72 degrees

• To calculate the tangent of 42 degrees

Why does the instructor use the sine of 18 degrees and the sine of 72 degrees in the calculation?

• Because they are complementary angles

• Because they are easier to calculate

• Because they are commonly known values

• Because they were derived in previous videos

What is the relationship between the cosine of an angle and the sine of its complement?

• They are always different

• They are both zero

• They add up to 180 degrees

• They are equal

What is the final expression for the exact value of the sine of 42 degrees?

• Square root of 3 over 8 minus 1/8 times the square root of 6 plus 1

• Square root of 5 over 8 plus 1/8 times the square root of 6 minus 1

• Square root of 2 over 8 plus 1/8 times the square root of 5 plus 1

• Square root of 6 over 8 minus 1/8 times the square root of 5 minus 1

How does the instructor verify the calculated expression for the sine of 42 degrees?

• By using a different trigonometric identity

• By using a calculator to check if it equals 42 degrees

• By comparing it with the cosine of 42 degrees

• By comparing it with the sine of 30 degrees