How to prove the cofunction identities using sum and difference formulas

The video tutorial explains the sum and difference identities for trigonometric functions, focusing on sine and cosine. It demonstrates how to apply these identities to verify that the left side of an equation equals the right side. The instructor emphasizes the importance of understanding the roles of U and V in the formulas and clarifies common misconceptions. The tutorial also covers the evaluation and simplification of trigonometric expressions using these identities.

What should you consider when you see sine, cosine, or tangent involving two angles?

• Consider the angle of elevation

• Use the sum and difference identities

• Use the law of sines

• Apply the Pythagorean identity

Which identity can sometimes be used instead of the sum and difference identities?

• Reciprocal identity

• Cofunction identity

• Double angle identity

• Pythagorean identity

When applying the sum and difference identities, how should you treat the negative sign in U - V?

• Distribute it to both U and V

• Ignore it completely

• Treat U and V as separate entities

• Add it to the final result

What is the result of sine of π/2?

• -1

• Undefined

• 1

• 0

What happens when you multiply any number by zero in trigonometric expressions?

• The result is zero

• The result is the number itself

• The result is one

• The result is undefined