2025 · Q71
In triangle ABC, angle A=30°, AB=7 cm, AC=12 cm. What is the area?
Elementary MathematicsGeometry: Lines, Angles and Triangles
- A21 cm^2
- B42 cm^2
- C84 cm^2
- D10.5 cm^2
Explanation
Area = (1/2)*AB*AC*sin(30 degrees) = (1/2)*7*12*(1/2) = 21 cm^2. The formula needs the angle included between the two known sides. Using sin(30) = 1/2 (not cos 30) is the point.