Since we have two sides that both equal 3.5, we know this is an isosceles triangle. We know that in isosceles, the “bottom” 2 angles (or the angles between the equal sides and the 3rd side) are equal.
This means the angle at the top of your triangle (so, the furthest one up/“North”) would be 55°.
We know that every triangle’s angles add up to 180°, and since we have two of three angles, we can easily find the third one (x).
x + 55 + 55 = 180
x + 110 = 180
x = 180 - 110
x = 70°
