is true only for equal to ? I would like a proof or well explanation.

Expand the left side using the angle sum identity for cosine:

This reduces to if the sine product is 0 and . This happens when where is any integer; that is, any even multiple of .

So technically the claim is false; it's true for infinitely many values of . But it is certainly true for rad.

i think it would be 43 movies that would have to be watched.

step-by-step explanation:

think about it. for the second plan, every month is 8 dollars. 8 x 12= 96. so thats the number for the second plan. now for the first plan, its annual meaning you have to pay 10 dollars every year. so now you have to get an equivalent amount of 86 since 96-10=86. 86 divided by 2 since every movie costs 2$ then you would have to watch 43 movies a year to get the same as the second plan. i really hoped this . have a wonderful day as well!