Hi there!
To solve, we must use the following trig identity:
sin(u - v) = sin(u)cos(v) - sin(v)cos(u)
We can rewrite the left hand side of the equation as:

Split the fraction:

First fraction reduces to 1:

Simpify each with common arguments:

Answer:
seems to easy to be true but the answer is 7/12 cause it's a fraction and it can't be simplified
Step-by-step explanation:
x²-y²=12
(x-y)(x+y)=12
but x-y=4
4(x+y)=12
x+y=12/4
x+y=3
lets make x the subject of the formula
x=3-y
since x-y=4
(3-y)-y=4
3-y-y=4
-2y=1
y=-1/2
then x=3-y
x=3-(-1/2)
x=(6--1)/2
x=7/2
therefore; x²+2xy+y
=(7/2)²+2×7/2×-1/2+(-1/2)
=49/4-7/2-1/2
=(49-14-2)/4
=33/4
=8.25
=8
Well I don't know how to show work on this one.
50. 2 3/4 is between 2 and 3, three times farther from two than three. Draw a dot in approximately that locations and mark it 2 3/4.
51. 4 1/3 is between 4 and 5, twice as far from five as from four. Draw a dot and mark it 4 1/3.