1 / 5

Aim: How do we develop and apply the formula for cos ( A

Aim: How do we develop and apply the formula for cos ( A. B )?. Do Now: Evaluate the following. 1. cos (60 ° – 30°). 2. cos 60 ° cos 30° + sin 60° sin30 °. 3. cos(60 ° + 30°). 4. cos 60 ° cos 30° – sin 60° sin 30°. HW: p.492 # 10,12,16,18 p.495 # 10,14,16,18.

maisie-barnett
Download Presentation

Aim: How do we develop and apply the formula for cos ( A

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Aim: How do we develop and apply the formula for cos (A B)? Do Now: Evaluate the following 1. cos (60° – 30°) 2. cos 60° cos 30° + sin 60° sin30° 3. cos(60° + 30°) 4. cos 60° cos 30° – sin 60° sin 30° HW: p.492 # 10,12,16,18 p.495 # 10,14,16,18

  2. Difference of two angles of cosine cos(A – B) = cos A cos B + sin A sin B Sum of two angles of cosine cos (A + B) = cos A cos B – sin A sin B

  3. We can use these formulas to find the exact values of non special angles Example: Find exact value of cos 75 cos 75 = cos(120 – 45) = cos 120 cos 45 +sin 120 sin 45 = • If Sin A = 3/5 with Example: in quadrant II and cos B = 5/13 with is in quadrant I, find cos (A – B). * First of all, find cos A and sin B cos A = – 4/5, sin B = 12/13 cos (A – B) = cos A cos B + sin A sin B = (- 4/5)(5/13) + (3/5)(12/13) = -20/65 + 36 /65 = 16/65

  4. Example: If is not in quadrant I ,and Is not in quadrant IV Find the value of

  5. APPLICATION: 1. Find the exact value of cos 15° 2. Use cos (A – B) to show cos(270° – x ) = – sin x 3. If and both A and B are in quadrant III. Find cos(A – B) 4. If Both angles are in quadrant III. Find the exact value of cos(x – y)

More Related