The degree measure of each of the three angles of a triangle is an integer. Which of the following cannot be the ratio of their measures?
A) 2:3:4
B)3:4:5
C)4:5:6
D)5:6:7
E)6:7:8

Question

The degree measure of each of the three angles of a triangle is an integer. Which of the following cannot be the ratio of their measures? 
A) 2:3:4 
B)3:4:5 
C)4:5:6 
D)5:6:7
 E)6:7:8

anonymous · Answer

One way of looking at this might be to find a number which is integrally divisible by 2, 3 and 4 or 3, 4 and 5, and so on...

anonymous · Answer

Or find LCM of 3/4/5, 4/5/6 and so on...

anonymous · Answer

Got it! If 2+3+4 = 9 divides 180, which it does (=20), then angles are 2times 20, 3 times 20 and 4 times 20, which add to 180.

B, C and D sums all divide into 180, but E's sum doesn't, so the answer is E