9
lesson pretestMultiple Choice

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Question 9 • Mathematics II

If triangle DEF has a 90 degrees angle at vertex cap e , which statements are true? Choose two correct answers.

Answer
A
The angle at vertex cap d is acute.
B
The angle at vertex cap f is obtuse.
C
The angle at vertex cap d is obtuse.
D
Triangle DEF is an obtuse triangle.
E
Triangle DEF is a right triangle.

Explanation

A triangle’s angles add up to 180°. Since angle E is 90°, angles D and F together make 90°, so each is less than 90° and acute. Therefore, angle D is acute, and triangle DEF is a right triangle.

AI-written and checked against the verified answer.

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