i don't know but i'm answering so your question doesn't get taken down before someone can answer :)
Taking Rhs
1/2 [sin(x+y)+ sin (x-y)]
using sinA + sin B = 2 cos (A+B)/2 cos( A - B)/2
1/2 [ 2 Cos ( x+y+x-y)/2 . Cos (x+y-x+y)/2]
=Cos 2x/2. Cos 2y/2 = Cos x . Cos y
Hence true
The cost of the mortgage is $81250
<h3>What are interests?</h3>
Interests are percentages of a principal
Given the following parameters
Principal = $65000
Rate = 7% = 0.07
Time = 5 years
<h3>Calculate the interest</h3>
I = PRT/100
I = 65000*0.07*25
I = 16,250
<h3>Determine the cost of the mortgage</h3>
Cost of mortgage = Principal + Interest
Cost of mortgage = 65000 + 16250
Cost of mortgage = 81,250
Hence the cost of the mortgage is $81250
Learn more on mortgage here: brainly.com/question/22846480
I’m pretty sure it is B
Hope I helped.