Question about an equilateral triangle with side 20

In one of my worksheets, I encountered an equilateral triangle with a sides == to 20. In addition, it was given with a height of 12, and I'm curious about whether this triangle is at all possible? When split into two 30-60-90 triangles, it has the sides:

hypotenuse = 20

base = 10

height = 12

which don't satisfy the Pythagorean theorem despite being a right angled triangle (100+144 =/= 400). I tried to solve a problem involving this triangle using trig functions and my answer came out wrong, so I'm wondering whether this is a valid given or if I'm missing something.