So you have an 8meter ladder that's resting against a wall. If you draw it out, the floor is the bottom of a triangle, the wall is the vertical side of the triangle, and the hypotenuse is the ladder itself. You're given the ladder length of 8 meters, so that's a given.

For a, 1 meter is the distance from the base of the wall to the bottom of the ladder... ie, the bottom leg of the triangle. Solve for the other leg.

For b, you're given the height of the wall (the vertical leg), so solve for the bottom leg.