Step-by-step explanation:
½ [cos(a − b) − cos(a + b)]
Using sum and difference formulas:
½ [cos a cos b + sin a sin b − (cos a cos b − sin a sin b)]
Distribute the negative:
½ (cos a cos b + sin a sin b − cos a cos b + sin a sin b)
Combine like terms:
½ (2 sin a sin b)
Simplify:
sin a sin b
Answer:
$ (7x+12)
Step-by-step explanation:
We have that,
Price of each cell phone plan = $x
Since, 3 friends pay extra $4 for the plan.
Thus, the amount paid by the three friends is $ 3(x+4).
Now, as the ramaining people do not pay the extra cost and there are 7-3 = 4 people remaining.
Thus, the amount paid by remaining people = $ 4x
Thus, the total cost of the plan will be $ [3(x+4) + 4x] = $ (7x+12).
Hence, the expression for the total cost of the seven plans is $ (7x+12).
Answer:425
Step-by-step explanation:
Answer:
i think x = 4
Step-by-step explanation:
