Answer: 67°
Explanation:
Hi, since the situation forms a right triangle (see attachment) we have to apply the next trigonometric function.
Cos α = adjacent side / hypotenuse
Where α is the angle of elevation of the ladder to the ground (x) the hypotenuse is the longest side of the triangle (in this case is the length of the ladder), and the adjacent side is the distance between the bottom of the ladder and the base of the cathedral.
Replacing with the values given:
Cos x = 10/26
Solving for x
x = arc cos 10/26
x = 67°
Feel free to ask for more if needed or if you did not understand something.