Given the trigonometry expression:
sin 3x = sin(2x+x),
In trigonometry identity;

The expression above will then become;

Recall that sin^2x + cos^x = 1, hence;

This shows that
(Proved!)
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Twice a number can be written as 2n.
Four times the number can be written as 4n.
If the sum of 2n and 4n equals 54, then:
6n = 54
Divide both sides by 6 to solve for n:
n = 9
-9 and 2 are like terms bc you can add them together
R example: 6 1/2 = 13/2 = 6.5
For the first example, six and a half is equal to thirteen halves, which
is then equal to six point five. To do this, the rule to turn a mix
number into a fraction is by multiplying the 2 with the 6 and then add
the answer to 1, which gives 13/2 (Remember to always give the same
denominator). Finally, thirteenth halves is equal to six point five
(because when you divide 13 by 2, you get 6 and one left over. To
continue dividing, add a 0 , and so 10 goes into 2 is five. so the
decimal is 6.5