Well visualize a 10 foot ladder leaning on a wall and how the space from the distance of the wall are gonna form an angle in this question it tells you it forms a 30 degree angle so your gonna go up 10 feet and out how much the angle is on a slant and multiply the two numbers?
the space between is what your determining.
/l
/ l < that is the wall
/ l
/ l
^that is the ladder
