Question

Pre calculus math question? help please?
The value 3pi/4 is a solution for the equation 3square root of 2 cos theta +2=-1

A. True

B. False

Answer 1

\[\bf 3\sqrt{2}\cos(\theta)+2=-1\]Is this what you mean? @StudentLearner

Answer 2

yes @genius12

Answer 3

Rearrange the equation to get:\[\bf \cos(\theta)=\frac{ -3 }{ 3\sqrt{2} }=-\frac{\sqrt{2}}{2}\]

Answer 4

so that means it would be false? :)

Answer 5

look at your Unit Circle

Answer 6

\(\frac{3\pi}{4}\) would be in the 2nd Quadrant

Answer 7

We know from our common trig values that:\[\bf \cos \left( \frac{\pi}{4} \right)=\frac{\sqrt{2}}{2}\]But that angle is in the first quadrant. Cosine is negative in the second and third quadrants. Hence the reference angles that will result in a negative value instead of a positive value will be:\[\bf x= \frac{3\pi}{4} \ or \ x=\frac{5\pi}{4}\]

@StudentLearner

Answer 8

so it is true :D thanks guys