Can someone help me pls

the only explanation to this is segment MN is tangent to circle L because it touches the circle L in one point

For MN to be tangent, angle N would need to be 90 degrees making the triangle a right triangle.

Using the Pythagorean theorem uses the base and the height to see if it equals what is shown for the hypotenuse. If it does it is tangent.

Hypotenuse = SQRT(18^2 + 80^2)

Hypotenuse = sqrt(324 + 6400)

Hypotenuse = sqrt(6724)

Hypotenuse = 82

This matches the 82 shown in the picture, so it is a right triangle, making MN tangent to circle L.

yes the total will be same because in both of them the expression.is rearranged but their sign remains the same hence it hss just been shuffled