The video tutorial explains how to simplify the expression sine(π/2 - X) using the difference formula for sine functions. Initially, the cofunction identity is mentioned, but the focus is on proving the expression equals cosine(X) through the sum and difference formulas. The tutorial provides a detailed step-by-step process, labeling the angles and applying the formula, leading to the evaluation and confirmation of the result.

What is the initial identity mentioned to simplify sine of π/2 - X?

• Sum identity

• Reciprocal identity

• Cofunction identity

• Product identity

Which formula is used to simplify the expression sine of π/2 - X?

• Sum formula for cosine

• Difference formula for sine

• Product formula for tangent

• Reciprocal formula for secant

In the difference formula for sine, what does the expression become after substituting U and V?

• Sine of U times cosine of V minus cosine of U times sine of V

• Sine of U times sine of V plus cosine of U times cosine of V

• Cosine of U times cosine of V minus sine of U times sine of V

• Cosine of U times sine of V plus sine of U times cosine of V

What is the value of sine of π/2?

• 1

• -1

• 0

• Undefined

After evaluating the trigonometric values, what does the expression simplify to?

• Tangent of X

• Secant of X

• Cosine of X

• Sine of X