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MCF3M1 Date: ___________ Lesson 1- Reviewing the Primary Trigonometric Ratios Recall: SOH CAH TOA A Sin = O – Opposite H – Hypotenuse A - Adjacent B O H Cos = A H Tan = O A C Note: To solve a triangle means to find all unknown sides and angles. You can use your calculator to find the sin, cos or tan of any angle. Example 1: Evaluate. a) sin 53˚ b) cos 86˚ c) tan 71˚ You can also use your calculator to find the value of an angle, given its sin, cos or tangent value. Example 2: Find the measure of each angle. a) sin A = 0.7183 b) cos C = 0.9781 c) tan X = 1.1788 We can also use trig to solve for missing side lengths and angles. Refer to the handout “What’s My Triaingle” for assistance with this. Example 3: Find the lengths of the missing sides (x) in the given triangles. a) 37o x What Do I Have? What Do I Need? 10 cm What Should I Use? MCF3M1 b) What Do I Have? x What Do I Need? 53o 17 cm c) What Should I Use? What Do I Have? 7.6 cm x What Do I Need? What Should I Use? 3.6 cm Example 4: Find the measure of the missing angles ( ). a) What Two Sides Do I Have? 12 cm What Should I Use? 5 cm b) What Two Sides Do I Have? 9 cm What Should I Use? 15 cm