Question

What is the length of the altitude of the equilateral triangle below

Answer 1

Using Sine.

Sine = Opposite / Hypotenuse

sin 60° = a / (6√3)                        But sin60° = √3/2

√3/2 = a/(6√3)

Cross multiply

2*a = 6√3 * √3

2a = 6 * √(3*3)

2a = 6*3

a = 6*3/2

a = 3*3 = 9

Option E.

Hope this helps.