There's a square, and inside is an equilateral triangle with the sides the same length as the square (the base of the triangle is the bottom of the square). Need to calculate the angle from the bottom left square corner, to the top of the triangle to the top left square corner.
75 degrees
The angle between the bottom left corner to the apex of the triangle is 30 degrees. (90 degrees - 60degrees)
The triangle bottom left corner of square to apex triangle to top left corner of the square is an isosceles triangle The side length of the equilateral triangle and the square are the same.
Therefore as the apex of the isosceles triangle = 30 degrees, the two base angles = (180 - 30)/2 = 150/2 = 75 degrees
Thanks. Yes, I agree. The only query I had initially was which angle the OP wanted, but I now agree it must be this 75 degree one (the angles being 30, 75,75)