What is the measurement of ∠A+∠B of a triangle shown as

[Max@Math Revolution]

What is the measurement of ∠A+∠B of a triangle shown as above figure?
1) ∠B<90o
2) ∠A is twice of ∠B

*An answer will be posted in 2 days.

[Max@Math Revolution]

If we modify the original condition and the question, from ∠A+∠B+∠C=180, we can find three variables (A, B, C) and one equation (∠A+∠B+∠C=180). In order to match the number of variables to the number of equations, we need 2 more equations. Hence, there is high chance that C is the correct answer. Using both the condition 1) and the condition 2), even if we substitute ∠A=2∠B, we cannot find the unique answer for ∠A+∠B. Hence, the correct answer is E.
- Forget conventional ways of solving math questions. In DS, Variable approach is the easiest and quickest way to find the answer without actually solving the problem. Remember equal number of variables and independent equations ensures a solution.