If Fx = Fy then the angle è which the vector F makes with the horizontal is of

0⁰
45⁰
90⁰
180⁰

sin 45 = cos 45

To determine the angle è between the vector F and the horizontal, we can use the principles of trigonometry.

Given that Fx = Fy, we can conclude that the vector F is equally inclined with respect to both the x and y-axes. This means that F forms a 45° angle with both the x-axis and y-axis.

Since we are interested in the angle between F and the horizontal, we need to consider the angle that F makes with the x-axis. Since the angle between F and the x-axis is 45°, the angle between F and the horizontal will be 90° - 45° = 45°.

Therefore, the correct answer is 45°.