S INE (S IN ): Opposite Leg/Hypotenuse C OSINE (C OS ): Adjacent Leg/Hypotenuse Example: Find sin A, cos A, sin B, and cos B › sin A = opposite / hypotenuse = 4 / 5 › cos A = adjacent / hypotenuse = 3 / 5 › sin B = opposite / hypotenuse = 3 / 5 › cos B = adjacent / hypotenuse = 4 / 5
Your Turn › Find each value › sin P › sin R › cos P › cos R 12 / 13 5 / 13 5 / / 13
A ski run 8395 feet long has a 20˚ angle of elevation. What is the vertical drop from the top of the run? › Looking for the angle opposite 20˚ › Given the hypotenuse Use the sin function › sin 20 = x/8395 › 8395 sin 20 = x › ft = x
You can use the sin -1 and cos -1 buttons on your calculator to find the measure of unknown angles, like we did yesterday with the tan -1 button. Example: Find the measure of H to the nearest degree. › We have the adjacent side (8) › We have the hypotenuse (9) › Use the cosine function › cos x = 8 / 9 › cos -1 ( 8 / 9 ) = x › 27˚ = x
YYOUR TURN ›F›Find the measure of R to the nearest degree ›7›71˚
Assignment › Worksheet #13-5 ThursdayChapter 13 Preview FridayChapter 13 Review Next MondayChapter 13 Test Next TuesdayQuarterly Preview Next Wed/ThurQuarterly Review Next Friday3 rd Quarterly Exam