1. Trigonometry 2. Finding Sides Of Triangles. L Adj’ Hyp’ 21m 23 o …………….

2. Finding The Unknown Side. Consider the triangle below: 35 o 14m Find the length of side L. L (1) Identify the two sides of the triangle. Opp Hyp’ (2) Choose the correct trig’ ratio. (3) Substitute the values into the ratio. (4) Calculate the sine value to 3d.p. (5) Cross multiply and solve for L. L = 8.04m to 2d.p. S O H C A H T O A

3. Example 2. Consider the triangle below: Find the length of side L. L (1) Identify the two sides of the triangle. Adj’ Hyp’ (2) Choose the correct trig’ ratio. (3) Substitute the values into the ratio. (4) Calculate the cosine value to 3d.p. (5) Cross multiply and solve for L. L = 19.34m to 2d.p. 21m 23 o SOHCAHTOASOHCAHTOA

4. What Goes In The Box ? (1) Identify the two sides of the triangle. (2) Choose the correct trig’ ratio. (3) Substitute the values into the ratio. (4) Calculate the trig’ angle value to 3d.p. (5) Cross multiply and solve for L to 1 d.p 74 o W 4.6cm (1) (2) (3) (4) (5) opp adj W = 16.1cm to 1 d.p. Calculate side W below.

5. Harder Example. The example below is trickier when it comes to the cross multiplication. 34 o L 24.6m (1) Identify the two sides of the triangle. (2) Choose the correct trig’ ratio. (3) Substitute the values into the ratio. (4) Calculate the trig’ angle value to 3d.p. (5) Cross multiply and solve for L to 1 d.p hyp’ adj’ L = 29.67m to 2.d.p.

6. What Goes In The Box? 2 Find the length of the unknown sides below: (1) 14cm A 25 o (2) 2.1m B 56 o (3) 13.9m C 42 o (4) 8.3m D 18 o 5.9cm 3.11m 9.3m8.73m