Four Quadrants

Hello Everyone, Regine de Lemos here! (:

Yesterday, Mr. Piatek handed out our second mental math quiz. Then he taught us a new lesson. He said in grade 11, we have to use all 4 quadrants when it comes to trigonometry.

Standard Position

The starting point is always the initial side, which can be found on the positive x-axis. The terminal side is the position after rotation.

When ever you go counter clockwise the angle is positive, but when ever you go clockwise the angle will be negative. T he negative sign is only used for directions. 

 

Quadrant I: if θ is in a standard position, the measure of the angle is between 0° and 90°.

Quadrant II: if θ is in a standard position, the measure of the angle is between 90° and 180°.

Quadrant III: if θ is in a standard position, the measure of the angle is between 180° and 270°.

Quadrant IV: if θ is in a standard position, the measure of the angle is between 270° and 360°.

Trigonometry (SOH CAH TOA)

sinθ =    opposite      = O =  y
            hypotenuse      H      r

cosθ =    adjacent      = A =  x
            hypotenuse     H     r

tanθ =    opposite    = O =  y
                adjacent       A      x

Radius is always equal to 1.

C.A.S.T RULE

Homework(s): Examples 1and 2 on page 17 and 18. Also try to do the Reference and Related Angles Table on page 19