1. 9.5 Apply the Law of Sines day 3 How do you use the law of sines to find the area of a triangle?

2. When you know the lengths of two sides and the measure of the included angles, you can find the area of a triangle. Find the Area of a Triangle

3. BiologyBlack-necked stilts are birds that live throughout Florida and surrounding areas but breed mostly in the triangular region shown on the map. Find the area of this region.

4. SOLUTION The area of the region is: Area = bc sin A 1 2 1 2 = (125) (223) sin 54.2° 11,300 Write area formula. Substitute. Use a calculator. The area of the region is about 11,300 square miles. ANSWER

5. Find the area of ABC with the given side lengths and included angle. 7. a = 10, b = 14, C = 46° SOLUTION The area of the region is: Area = ab sin C 1 2 1 2 = (10) (14) sin 46° 50.4 Write area formula. Substitute. Use a calculator. The area of the region is about 50.4 square units. ANSWER

6. Find the area of ABC with the given side lengths and included angle. 8. a = 19, c = 8, B = 75° SOLUTION The area of the region is: Area = ac sin B 1 2 1 2 = (19) (8) sin 75° 73.4 Write area formula. Substitute. Use a calculator. The area of the region is about 73.4 square units. ANSWER

7. Find the area of ABC with the given side lengths and included angle. 9. b = 11, c = 7, A = 120° SOLUTION The area of the region is: Area = bc sin A 1 2 1 2 = (11) (7) sin 120° 33.3 Write area formula. Substitute. Use a calculator. The area of the region is about 33.3 square units. ANSWER

8. Find the area of ABC with the given side lengths and included angle. 10. a = 20, b = 24, C = 87° SOLUTION The area of the region is: Area = ab sin C 1 2 1 2 = (20) (24) sin 87° 239.7 Write area formula. Substitute. Use a calculator. The area of the region is about 239.7 square units. ANSWER

9. How do you use the law of sines to find the area of a triangle?

10. 9.5 Assignment, day 3 p. 590, 29-41 all No work is the same as a missing problem.