It is true as A consist {7,8,9,10,11,12} and B consists of{9,11,13} and C consist of {7,8,10,12} and D has{7,12} there are the set of numbers from 7 to 13 only so the answer is true that U={7,8,9,10,11,12,13}.
you would need to multiply the 3 by 2 to get 6. the reason being since 8 can be created by multiplying 4 by 2. since their equivalent, you need to do the same and multiply 3 by 2 to keep them equal
The answer is DE = 27.81 in. Explanation: find the missing angle first, and put it into the equation for the law of sin ( sin(A)/a = sin(B)/b). Solve for the missing length, and you have the missing side to the triangle.