Determine whether each expression below is always, sometimes, or never equivalent to sin x when 0° < x < 90° ? Can someone help me :(

--- Never true

--- Always true

---- Sometimes true

---- Sometimes true

Step-by-step explanation:

Given

Required

Determine if the following expression is always, sometimes of never true

Expand using cosine rule

So, we have:

Hence: (a) is never true

Expand using cosine rule

So, we have:

Hence: (b) is always true

If

Then:

Divide both sides by 2

(c) is only true for

Hence: (c) is sometimes true

If

Then:

Divide both sides by 2

(d) is only true for

Hence: (d) is sometimes true

arithmetic sequence: a sequnce in which the diffrence between any two consecutive terms is the same

step-by-step explanation:

the graph on the bottom right