Answer: No a triangle cannot have a right angle and an obtuse angle.
Explanation: It would violate the theorem of the sum of the interior angles of a triangle summing up to 180 degrees. We know that sum of all interior angles of a triangle is 180 degrees. If we assume that one angle is right angle of 90 degrees and other angle be obtuse angle of x such that x> 90 degrees. Sum of the 2 angles is then 90+x>180 degrees. It cannot be possible due to equation. Therefore our initial assumption of x>90 degrees is incorrect and so the statement is false by the method of indirect proof.
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