If the lengths of the sides of a triangle are a , b , and 7, which of the following could be the value of a – b ?
I and II only
II and III only
I, II, and III
Use the third side rule: The third side is greater than than the difference of the rest two sides and smaller than the sum of those two sides.
Suppose three sides are 3, 4, and x: (4-3) < x < (3+4).
If so, (a-b) < 7. That is (a-b) can be 4 but not 7 or 12.