The cofunction of cos is sin(90-x)
90 degrees is equal to PI/2
The cofunction becomes sin(PI/2 - 2PI/9)
Rewrite both fractions to have a common denominator:
PI/2 = 9PI/18
2PI/9 = 4PI/18
Now you have sin(9PI/18 - 4PI/18)
Simplify:
Sin(5PI/18)
Answer: Is C
Your answer: C
<h3>
Answer: x-2y = -8</h3>
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Explanation:
Multiply both sides by 2 to clear out the fraction
y = (1/2)x+4
2y = 2[ (1/2)x + 4 ]
2y = 2*(1/2)x + 2*4
2y = x + 8
Then move the x term over to the left side
2y = x+8
2y-x = 8
-x+2y = 8
Optionally we can multiply both sides by -1
-x+2y = 8
-1*(-x+2y) = -1*8
x-2y = -8
This is in standard form Ax+By = C with A = 1, B = -2, C = -8
The reason why I multiplied both sides by -1 was to make A > 0 which is what some textbooks use as convention. Of course -x+2y = 8 is equally valid too.
