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# Sine rule

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1. Work out the area of the triangle PQR. Give your answer correct to 3 significant figures. Angle R is 42 degrees. Angle P is 85 degrees. The length of RQ is 15.6 cm. Use 1/2 ab Sin C
2. Angle Q = 53 degrees

15.6cm / sin(53) = b / sin(42)

15.6 / sin(53) * sin(42) = b = 13.0703cm

1/2 * 15.6 * 13.0703 * sin(85) = 102cm^2
3. (Original post by Elisa2000)
Work out the area of the triangle PQR. Give your answer correct to 3 significant figures. Angle R is 42 degrees. Angle P is 85 degrees. The length of RQ is 15.6 cm. Use 1/2 ab Sin C
65.2cm2

180 degrees in a triangle
180-85-42=53
angle Q is 53 degrees

sine rule PQ= 15.6/sin(85) all multiplied by sin(42)
PQ=10.7cm

Area= 1/2 X 10.7 X 15.6 X sin(53)
area = 65.2cm2

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