If tana+sina=m and tana-sina=n. prove that m^2-n^2=4√mn

Let and . Then

and

The expression under the square root can be rewritten as

Recall that

so that

and assuming and , we end up with

so that

as required.

5x+10 is the correct one

hope this

9 sandwiches per hour

step-by-step explanation:

when we have a rate, we want a 1 in the denominator

27/3 = 9

27 sandwiches/ 3 hours = 9 sandwiches/hour