A triangle always has
- exactly one right angle.
- at least two acute angles.
- exactly two acute angle.
Explanation
Because the three angles total 180 degrees, at most one of them can be 90 degrees or larger, which forces the other two to be acute (under 90 degrees). A triangle need not contain any right angle, so "exactly one right angle" is false, and it always has at least two acute angles.
muhammad shafiq asking:
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Community Comments (1)
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tsukiyo92 Posts: 13 15.07.2014 / 03:50
Definition:
Right angle = 90°
Acute Ange < 90° (less than 90°)
Obtuse Angle >90° <180°
We need to consider all type of triangle (2D0, total 180°)common:
Right Angle Triangle= one 90°, 2 other sum up to 90°
Equilateral Triangle= all three corner 60°
Since equilateral triangle have no 90°, neither exactly 2 acute angle, so second option is the answer. (which hold true to all type of 2D triangle)
Triangle do ATLEAST have 2 acute angle, just draw alot different triangle to figure out yourself.
Or mathematical method: (alot of thought, may be confusing)
Triangle have 3 corners with total of 180°. Few possibiliy:
If you have 1 right angle: 180-90=90° left, so there must be 2 acute angle.
If you have 1 obtuse angle,eg.: 180-160=20°, remain 2 angle are acute angle also.
If there is no obtuse nor right angle, then remain is 3 acute angle.
Right angle = 90°
Acute Ange < 90° (less than 90°)
Obtuse Angle >90° <180°
We need to consider all type of triangle (2D0, total 180°)common:
Right Angle Triangle= one 90°, 2 other sum up to 90°
Equilateral Triangle= all three corner 60°
Since equilateral triangle have no 90°, neither exactly 2 acute angle, so second option is the answer. (which hold true to all type of 2D triangle)
Triangle do ATLEAST have 2 acute angle, just draw alot different triangle to figure out yourself.
Or mathematical method: (alot of thought, may be confusing)
Triangle have 3 corners with total of 180°. Few possibiliy:
If you have 1 right angle: 180-90=90° left, so there must be 2 acute angle.
If you have 1 obtuse angle,eg.: 180-160=20°, remain 2 angle are acute angle also.
If there is no obtuse nor right angle, then remain is 3 acute angle.
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