1. Do Now: A point on the terminal side of an acute angle is (4,3)
Aim: How do we define trig functions by quadrant?
Do Now: A point on the terminal side of an acute
angle is (4,3)
a) Draw the angle in standard position
b) Find the distance between the point
and the origin
HW: p.372 # 6,8,14,16,18,20,22,24,26,27

2. y 5 3 x 4
The distance is the radius and the hypotenuse of the triangle in the standard position.

3. In general, the horizontal side of a triangle is x, the vertical side of a triangle is y and the hypotenuse is r (radius) r y x

4. Although we used to say there is no negative measurement, in trigonometry there are negative measurement depend on the position of the terminal side. But there is no negative radius. 3 -4 4 -4 -3 -3

5. From the above observation, we notice that the acute angle results in different trig ratios in the quadrants.
Quadrant I:
Quadrant II:
Quadrant III:
Quadrant IV:

6. We can use the saying” All Students Take Chinese” to remember ASTC.
Which reminds us that:
In quadrant I All three functions are positive,
In quadrant II Sine is positive
In quadrant III Tangent is positive
In quadrant IV Cosine is positive

7. Determine the signs for the following functions:
sin b) sin 200
c) sin d) cos 225
e) cos f) cos 195
g) tan h) tan 300

8. Name the quadrant: a) b) c)
and d)
and e)
and
and f) g)
and