You leaned the ladder against your house at a 30 degrees angle -> This create a right triangle, with a 30 degree angle and your ladder is the hypotenuse.
The foot of the ladder is 7 feet from the foot of your house -> The opposite side = 7 feet
In a right triangle, the side that is opposite to a 30 degree angle = 1/2 of the hypotenuse
Since your ladder is the hypotenuse, and the opposite side is opposite to the 30 degree angle, your ladder is 7 x 2 = 14 ft long.
