Section 9.3 Double-Angle, Half-Angle, & Reduction Formulas Video

How can the reduction identity for cosine of 2x be derived from the Pythagorean identity?

• By using the sum of angles identity

• By isolating cosine squared x and substituting it back

• By isolating sine squared x and substituting it back

• By using the double angle identity for sine

What is the first step to eliminate square roots in the half angle formula for tangent?

• Multiply by cosine of x over sine of x

• Multiply by sine of x over cosine of x

• Multiply by 1 minus cosine of x over 1 minus cosine of x

• Multiply by 1 plus cosine of x over 1 plus cosine of x

What is the double angle identity for sine of 2x?

• 2 sine x cosine x

• sine squared x minus cosine squared x

• 2 cosine squared x minus 1

• 1 minus 2 sine squared x

If cosine of x is negative one half, what is the adjacent side in a right triangle with hypotenuse 2?

• 1

• Square root of 2

• Square root of 3

• 2

What is the value of sine of 2A if sine of A is 12/13 and cosine of A is 5/13?

• 120/169

• 144/169

• 60/169

• 24/169

What is the simplified form of 2 cosine squared of 37 degrees minus 1?

• sine of 74 degrees

• sine of 37 degrees

• cosine of 74 degrees

• cosine of 37 degrees

How do you simplify cosine squared of an angle minus sine squared of the same angle?

• cosine of double the angle

• sine of double the angle

• tangent of double the angle

• cotangent of double the angle

Which identity is used to verify that 2 sine x cosine x equals sine of 2x?

• Pythagorean identity

• Half-angle identity

• Double-angle identity

• Sum-to-product identity

What is the result of multiplying sine of x over cosine of x by tangent squared of x?

• tangent of x

• tangent squared of x

• sine squared of x

• tangent cubed of x

What is the simplified form of cosine squared of 8x minus sine squared of 8x?

• sine of 16x

• cosine of 4x

• sine of 4x

• cosine of 16x