Question 47
Triangles and QuadrilateralsIn the figure below ΔABC and ΔAED are in adjacent planes. AB = AC = 5cm, BC = 6cm and <ADE = 60°, then AE is equal to
- A.3√2
- B.2√3
- C.√3/2
- D.2/√3
- E.3/√2
Show the answer and explanation
Answer: B (2√3)
Explanation
D is the mid-point of BC, so AD = √(5² − 3²) = 4cm. Triangle AED is right-angled at E, so AE = AD sin 60° = 4 × √3/2 = 2√3.