What's the distance between the two points -6,4 and -1,9

The pyramid below was dissected by a horizontal plane which shape describes the pyramid horizontal cross section

Worth 30 points! in this diagram, both polygons are regular. what is the value, in degrees, of the sum of the measures of angles abc and abd?

Jack has a rectangular piece of land, the area of which is represented by a1 = 9.5l. his brother has a different rectangular piece of land, the area of which is represented by a2 = l(14 − l). let a represent the area in square meters and l represent the length in meters of the pieces of land. the two equations plotted on a graph meet at a point as shown in the image