The vertical distance from S to T is 3.5 units The horizontal distance from S to T is 12 units So we have a right triangle forming with the legs of 3.5 and 12. The hypotenuse is x
Use the pythagorean theorem a^2+b^2 = c^2 3.5^2 + 12^2 = x^2 12.25+144 = x^2 156.25 = x^2 x^2 = 156.25 x = sqrt(156.25) x = 12.5