(1) Sin 186

(2) tan 150

(3) cos(-65)

#### MarkFL

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 $$\displaystyle 0^{\circ}\le\theta<360^{\circ}$$?

#### Greenstxr

I have an idea just wanted to see if I was correct without actually embarrassing myself. Can you answer the first question number 1?

#### MarkFL

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)

#### Greenstxr

Lol ok cool I have no idea when it comes to sin 186... Or which quadrant it would be in.

#### MarkFL

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°?

#### Greenstxr

Guessing 3rd quadrant 180 and 270

#### MarkFL

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?

Negative?