Find the exact value of cos 7x/12

I suppose x should be π.

Recall the double angle identity for cosine:

Then remember for , we have .

Let . Plugging this into the equation above gives

Take the square root of both sides; this introduces two possible values, but we know should be positive, so

unless if u could do my questions, if not i wouldn't want to

let x be the money she spent so that she can earn the free t-shirt.

since, she already spent $112.49

⇒

also, as per the statement: jennifer must spend $250 or more in order to qualify for a free t-shirt at the store.

then,

we have an inequality i.,e

subtract 112.49 from both sides we get;

therefore, $137. 51 more money does jennifer need to spend so that she can earn the free t-shirt