Amy's Reflection #10

This week we covered quite a lot in trig and this is some of the stuff i understand:

Sector of a Circle:

1. s = rθ

2. k = θ/2 r^2

(**Note: r = radius, θ = angle, s= arc length, & k = area of sector)

Example #1:

Find the length of the arc of a circle with radius 4 cm and central angle 5.1 radians.

s = rθ

= 4 × 5.1

= 20.4 cm

Example #2:

Find the area of the sector with radius 7 cm and central angle 2.5 radians.

k = θ/2 r^2

= (2.5)/2 (7)^2

= 61.25

Reference Angles:

1. The reference angle in the 1st quad is equal to the angle measure.

Example- θ = 60 = 60

2. To find the reference angle in the 2nd quad just subtract the angle from 180°.

Example- θ = 130° = 180° -130°= 50°

3. To find the reference angle in the 3rd quad subtract 180° from the angle given.

Example- θ = 240° = 240° - 180° = 60°

4. To find the reference angle in the 4th quad simply subtracting the angle from 360° will provide the reference angle in the 4th quad.

Example- θ = 315° = 360° -315° = 45°

I need help in finding the inverse. if someone could explain that to me, i'd really apprieciate that...oh people, don't forget we have a quiz on monday & our chapter 7 test is on tuesday..