#1**+1 **

You'll just have to use a calculator to find cos (-3/2 degrees) = .999657

or if you need cos ( -3/2 radians) = .070737

ElectricPavlov
Mar 4, 2018

#2**+1 **

\(tan \theta = -\frac{3}{2}\\ \)

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Think about \(tan \theta = +\frac{3}{2} \) first

Draw a right angled triangle.

Mark an acute angle as theta.

opp = 3

adj=2

so hypotenuse = \(\sqrt{9+4}=\sqrt{13} \)

So for this triangle \(cos\theta= \frac{2}{\sqrt{13}}=\frac{2\sqrt{13}}{13}\)

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Now, tan is negative in the 2nd and 4th quadrant

In the 2nd quad Cos is negative and in the 4th quad Cos is positive.

So

\(cos\theta=\pm\frac{2\sqrt{13}}{13}\)

Melody
Mar 4, 2018