Can anyone answer the following 3 questions? And state quadrant?

(1) Sin 186

(2) tan 150

(3) cos(-65)

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- Jan 23rd 2013, 10:44 AMGreenstxrQuadrant
Can anyone answer the following 3 questions? And state quadrant?

(1) Sin 186

(2) tan 150

(3) cos(-65) - Jan 23rd 2013, 12:42 PMMarkFLRe: Quadrant
Let's look at the quadrants first...assuming the arguments are in degrees, can you state what range of degrees the 4 quadrants encompass, for $\displaystyle 0^{\circ}\le\theta<360^{\circ}$?

- Jan 23rd 2013, 12:46 PMGreenstxrRe: Quadrant
I have an idea just wanted to see if I was correct without actually embarrassing myself. Can you answer the first question number 1?

- Jan 23rd 2013, 12:56 PMMarkFLRe: Quadrant
Quadrant I: $\displaystyle 0^{\circ}<\theta<90^{\circ}$

Quadrant II: $\displaystyle 90^{\circ}<\theta<180^{\circ}$

Quadrant III: $\displaystyle 180^{\circ}<\theta<270^{\circ}$

Quadrant IV: $\displaystyle 270^{\circ}<\theta<360^{\circ}$

So, in which quadrant is $\displaystyle 186^{\circ}$? And don't worry about embarrassing yourself, there is no shame in asking questions, the only shame is in not asking when you don't know. (Nod) - Jan 23rd 2013, 01:03 PMGreenstxrRe: Quadrant
Lol ok cool I have no idea when it comes to sin 186... Or which quadrant it would be in.

- Jan 23rd 2013, 01:10 PMMarkFLRe: Quadrant
Which range of values does 186° match? Is it in between 0° and 90°, or in between 90° and 180°, or in between 180° and 270°, or in between 270° and 360°?

- Jan 23rd 2013, 01:15 PMGreenstxrRe: Quadrant
Guessing 3rd quadrant 180 and 270

- Jan 23rd 2013, 01:17 PMMarkFLRe: Quadrant
Yes, since 180 < 186 < 270, we know 186° is a quadrant III angle. As such, what can we expect the sign of sin(186°) to be? Will it be negative or positive?

- Jan 23rd 2013, 01:21 PMGreenstxrRe: Quadrant
Negative?

- Jan 23rd 2013, 01:43 PMGreenstxrRe: Quadrant
So is that the answer?

- Jan 23rd 2013, 03:11 PMMarkFLRe: Quadrant
Are you instructed to use your calculator to get a decimal approximation or to use identities to obtain an exact answer?