For 1: Use pythagorean theorem because of the radius tangent theorem(point of contact = 90 degrees) 12 is the hypotenuse (the right angle points at the hypotenuse) Therefore: (9)^2 + (x)^2 = (12)^2 81 + x^2 = 144 Subtract 81 from both sides of the equation x^2 = 63 Square root both sides to get rid of square on x and isolate the variable The square root of 63 = 7.93 (roughly)