Area of a circle order to arrive at the formula for the area of a disk. Consider unwrapping the concentric circles to straight strips. This will form a right angled triangle with r as its height and 2r (being the outer slice of onion) as its base. Finding the area of this triangle will give the area of the disk The opposite and adjacent angles for this triangle are respectively in degrees 9.0430611..., 80.956939... and in radians 0.1578311... , 1.4129651... Explicitly, we imagine dividing up a circle into triangles, each with a height equal to the circle's radius and a base that is infinitesimally
Distance from a point to a line has coordinates: Horizontal and vertical lines In the general equation of a line, "ax" + "by" + "c" = 0, "a" and "b" cannot both be zero unless "c" is also zero, in which case the equation does not define a line. If "a" = 0 and "b" 0, the line is horizontal and has equation "y" = -"c"/"b". The distance from ("x", "y") to this line is measured along a vertical line segment of length |"y" - (-"c"/"b")| = |"by" + "c"| / |"b"| in accordance with the formula. Similarly, for vertical lines ("b" = 0) the distance between