Download presentation

Presentation is loading. Please wait.

Published byGrady Hollyfield Modified over 2 years ago

1
Xavier Noel Albrecht Salena Lemieux

2
Introduction

3
Explanation Law of Cosine— a 2 =b 2 +c 2 -2bcCosA b 2 =a 2 +c 2 -2acCosB c 2 =a 2 +b 2 -2abCosC

4
Explanation First you need to identify what you have You need to have three sides (SSS) OR two sides and an angle in between them (SAS) Put the information that you have and put it into the correct formula Solve for the missing side or angle

5
Example #1- Finding a side a² = b² + c² −2(a)(b)cos(A°) a² = 20² + 13² −2(20)(13)cos(66°) a² = −520cos(66°) a² = 569 −211 a² = 358 a = 358 1/2 a = 18.9

6
Example #2-Finding a side a² = b² + c² −2(b)(c)cos(A°) a² = 52² + 16² −2(52)(16)cos(115°) a² = 2, − 1,664cos(115°) a² = 2,960− 1,664(-.423) a² = 2, a² = 3663 a=3663 1/2 a=60.5

7
Example #3 Finding an angle a² = b² + c² −2(a)(b)cos(A°) 14² = 20 ² + 12² −2(12)(20)cos(A°) 14²- 20 ² - 12² = (12)(20)cos(A°) -348=-480cos(A°) 0.675=cos(A°) cos -1 (0.25) Cos(A°)=47.5°

8
Example #4- Finding an angle a² = b² + c² −2(a)(b)cos(A°) 25² = 32² + 37² −2(32)(37)cos(A°) 625 = 2393 − 2,368 cos(A°) -1760=-2,368cos(A°) =cos(A°) cos -1 (0.7432) Cos(A°)=42°

9
Checking The longest side has the largest angle and the smallest side has the smallest angle This won’t give you the exact answer but it will help see if you have the right idea

10
Activity cosines-flash-cards/ cosines-flash-cards/ Who ever can get the most right wins

11
Assessment a=12 b=21 C=95° Find side c. A) B)30 C) a=3 b=7 c=6 Find angle B° A)126.83° B)90° C)83.621° c=8 B=131 a=13 Find side b A)53 B)9.825 C)528.9 a=27 b=19 c=24 Find angle A° A)70° B)76.817° C)71.867° A=55° b=12 c=7 Find side a A)3.83 B)15 C)9.831 A=55° b=14 c=23 Find side a A) B)20 C) C=42° b=12 a=14 Find side c A)9.503 B)15 C)30.59 A=82° b=22 c=31 Find side a A)40 B) C) C=65° a=19 b=22 Find side c A)50 B) C) B=31° a=8 c=11 Find side b A)5.843 B)3.485 C)12

12
Work Cited of-cosines-formula-examples.php of-cosines-formula-examples.php cosines-flash-cards/ cosines-flash-cards/ Notes from class Problems from book

Similar presentations

© 2016 SlidePlayer.com Inc.

All rights reserved.

Ads by Google