Question

An equilateral triangle has a side length of 10 units. What is it’s area?

Answer 1

`25√(3)=43.3\ \mathrm{units}`

Explanation:

Area of a triangle =
`(1)/(2)ab\textrm{sin}(\theta)` where
`a` and
`b` are the sides of the triangle and
`\theta` is the angle between those two sides.

The side length are 10, and since its an equilateral triangle, the angle is 60 degrees. Thus, the area becomes
`(1)/(2)(10)(10)\textrm{sin}(60)=25√(3)=43.3\ \mathrm{units}`