AM is perpendicular to BD because they from a right angle and the definition of perpendicular is when two lines meet they form a right angle. AM goes straight down and BD form the horizontal line. These two lines form a right angle so AM is perpendicular to BD.
We have to rewrite the expression so that it has no denominator. For example: 1 / x = x^(-1) 1/8 = 8^(-1); 1/x^(4) = x^(-4); 1/y^(3) = y^(-3); 1/z = z^(-1).
