Tuesday, May 27, 2014

find all real numbers in this interval (o, 2 pi) that satisfy this equation. round to the nearest tenth. cos x(square root symbol) 3 = 3(square...

If the equation is cos x*sqrt 3 = 3*sqrt (3*sin x), we'll
raise to square both sides to remove the square root from both
sides:


3(cos x)^2 = 9*3*sin
x


We'll divide by 3 both
sides:


(cos x)^2 = 9*sin
x


We'll use the Pythagorean identity to express cos x with
respect to sin x:


(cos x)^2 = 1 - (sin
x)^2


1 - (sin x)^2 = 9*sin
x


We'll subtract 9sin x both
sides:


- (sin x)^2 - 9*sin x + 1 =
0


(sin x)^2 + 9*sin x - 1 =
0


We'll replace sin x by
t:


t^2 + 9t - 1 = 0


We'll
apply quadratic formula:


t1 = [-9 + sqrt(9^2 -
4*1*(-1))]/2*1


t1 =
(-9+sqrt85)/2


t1 = 0.1097


t2 =
(-9-sqrt85)/2


t2 = -9.1097


sin
x = t1 => sin x = 0.1097 => x = arcsin 0.1097 => x = 6.2980 degrees
(1 st quadrant) or x = 180 - 6.2980 = 173.702 degrees (2 nd
quadrant)


sin x = -9.1097 impossible since the values of
the function sine cannot be smaller than
-1.


Therefore, the solutions of the equation
are expressed in degrees and they are: {6.2980 ;
173.702}.

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