4(a) . a^2 + b^2 = c^2....where a and b are the legs and c is the hypotenuse           12^2 + b^2 = 13^2           b^2 = 13^2 - 12^2           b^2 = 169 - 144           b^2 = 25           b = sqrt 25           b = 5 <== ur missing leg(t) = 5   (b)   a^2 + b^2 = c^2           a^2 + 9^2 = 12^2           a^2 = 12^2 - 9^2           a^2 = 144 - 81           a^2 = 63           a = sqrt 63           a = 7.9 <== ur missing leg(a) (c) a^2 + b^2 = c^2      6^2 + 9^2 = c^2       36 + 81 = c^2       117 = c^2        sqrt 117 = c        10.8 = c <== ur hypotenuse (x)