Answer:
<u>The answer is</u>
The angle at vertex D is acute
Triangle DEF is a right triangle
Step-by-step explanation:
<u>Statements</u>
<u>case A)</u> Triangle DEF is an obtuse triangle
The statement is false
The triangle DEF has no angle greater than
Triangle DEF is a right triangle, because has an angle equal to
<u>case B)</u> The angle at vertex D is acute
The statement is true
Because
∠D+∠F=
so
Angle D is less than
<u>case C)</u> The angle at vertex F is obtuse
The statement is false
Because
∠D+∠F=
so
Angle F is not greater than
<u>case D)</u> Triangle DEF is a right triangle
The statement is true
Because, angle at vertex E is equal to
<u>case E)</u> The angle at vertex D is obtuse
The statement is false
Because
∠D+∠F=
so
Angle D is not greater than