If you cut an isosceles triangle in half, you get a right angled triangle. You can work out 'd' or the hypotenuse using Pythagoras's theorem: a^2 + b^2 = c^2
Because we are looking at half of the triangle, we have to half the base, 14m. So you get 7m. But the height of the triangle, 5m, stays the same.
So if you out the figures into the formula you'd get: 7^2 + 5^2 = d^2
To get 'd' you have to square root the first half of the equation. So you get: √7^2 + 5^2 = d
