Valentin K. answered 03/18/24
Expert PhD tutor in Algebra, Geometry, Statistics, and Physics
This is an equilateral triangle. If the base is along the x-axis at points (0,0) and (10,0), it has a side length of 10 - 0 = 10 units.
Draw the equilateral triangle. By symmetry, the third point will be hanging above the middle of the base at x = 10/2 = 5.
Split the triangle into two right triangles by dropping the height from the third point towards the base.
Take the left right triangle - it has a base of 10/2 = 5 units along the x-axis, an angle of 60 degrees at the base, and a height y.
Using trigonometry for the right triangle: tan60° = y/5
Therefore, y = 5tan60°
The coordinates of the third point are (x, y) = (5, 5tan60°).