In triangle PQR, PQ = 9 cm, PR = 13 cm and the area of triangle PQR is 45\ \text{cm}^2. Using \text{Area} = \tfrac{1}{2}ab\sin C, find the acute angle \angle QPR, correct to 1 decimal place.

EM-3058

Area of a triangle (½ab sin C)

E Math · Secondary 4 · Medium · Area of a triangle (½ab sin C)

In triangle

PQR

PQ = 9

cm,

PR = 13

cm and the area of triangle

PQR

45\ \text{cm}^2

.

Using

\text{Area} = \tfrac{1}{2}ab\sin C

, find the acute angle

\angle QPR

, correct to 1 decimal place.

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