The compass marks all point equidistant from a common center. Where the arc centered on B and including A intersects the arc centered on A and including B, the three points A, B and the intersection have identical distances between any pair of the three points. A triangle with equal sides is called equilateral.
First, you multiply 2.1 by 3.2, which gives you the answer of 6.72. Then, you multiply 10-2 by 10-4. One rule about multiplying exponents, you just add the exponents. So 10-2 x 10-4 = 10-6. Finally you get the answer of C. 6.72 x 10-6.
