After it dried, which took about two hours, I sanded it flush with the wood using #120-grit sandpaper, then stained the entire shelf. You have to look closely to see the spot where the nail hole had been! Quick Tip: Always sand in the direction of the grain of the wood to avoid unsightly scratches.
In the picture below, the angles â ABC, â BCA and â CAB are the three interior angles of the triangle. An exterior angle is formed by extending one of the sides of the triangle; the angle between the extended side and the other side is the exterior angle. In the picture, angle â ACD is an exterior angle. Euclid's exterior angle theorem
The third line that intersects the two lines is called the transversal. Co-interior angles always lie on the same side of the transversal, never on opposite sides. The sum of a pair of co-interior angles is always equal to 180 degrees if the two lines are parallel to each other. When the two lines are not parallel, the sum of the two co-interior angles would not be exactly 180 degrees. This is an important axiom in geometry.