Which of the following choices demonstrates the converse of the Pythagorean theorem correctly? (Assume that angle C is the right angle in the triangle ABC. a, b, c stands for side lengths BC, AC, and AB respectively) A) If a2 + c2= b2, it’s a right triangle
B) If c2 + b2=a2, it’s a right triangle
C)If a2 + b2=c2, it’s a right triangle
D) None of the above.

For every corresponding pair of cross sections, the area of the cross section of a sphere with radius r is equal to the area of the cross section of a cylinder with radius and height 2r minus the volume of two cones, each with a radius and height of r. a cross section of the sphere is and a cross section of the cylinder minus the cones, taken parallel to the base of cylinder, is the volume of the cylinder with radius r and height 2r is and the volume of each cone with radius r and height r is 1/3 pie r^3. so the volume of the cylinder minus the two cones is therefore, the volume of the cylinder is 4/3pie r^3 by cavalieri's principle. (fill in options are: r/2- r- 2r- an annulus- a circle -1/3pier^3- 2/3pier^3- 4/3pier^3- 5/3pier^3- 2pier^3- 4pier^3)