Trig Ratios C 5 2 A M 4. If C = 20º, then cos C is equal to: Be sure to discuss if C = 20, then sin C would equal ? 4. If C = 20º, then cos C is equal to: A. sin 70 B. cos 70 C. tan 70

Skills Check

UNIT QUESTION: What patterns can I find in right triangles? CCGPS Geometry UNIT QUESTION: What patterns can I find in right triangles? Standard: MCC9-12.G.SRT.6-8 Today’s Question: How do we use trig ratios to find the missing sides and angles of a triangle?

Finding a missing angle Finding a missing angle. (Figuring out which ratio to use and an inverse trig button.)

Ex: 1. Figure out which ratio to use. Find x Ex: 1 Figure out which ratio to use. Find x. Round to the nearest tenth. O 20 m 40 m A x Shrink yourself down and stand where the angle is. Identify the given sides as H, O, or A. What trig ratio is this?

Ex: 2. Figure out which ratio to use. Find x Ex: 2 Figure out which ratio to use. Find x. Round to the nearest tenth. O H 15 m 50 m x Shrink yourself down and stand where the angle is. Identify the given sides as H, O, or A. What trig ratio is this?

Ex. 3: Find . Round to the nearest degree. 17.2 9 A

Ex. 4: Find . Round to the nearest degree. 7 23 H

Ex. 5: Find . Round to the nearest degree. 200 O 400 H

When we are trying to find a side we use sin, cos, or tan. When we are trying to find an angle we use (INVERSE) sin-1, cos-1, or tan-1.