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A triangle is a three-sided figure with three angles, two or three of which (depending on the triangle) must be acute angles. The sum of all of the angles has to equal 180° - no more, no less. An acute angle is an angle of less than 90°. If one of the angles of a triangle is 90° or more (it is a right angle or obtuse angle) the SUM of the other two angles cannot exceed 180° minus the degree of the first angle. Therefore the two remaining angles must be less than the first angle, which means that they have to be acute angles.

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Q: Why do all triangles have acute angles?
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Do all triangles have two acute angles?

INCORRECT: No because there is a obtuse triangle and a right triangleCORRECT ANSWERYes all triangles have at least two acute angles. Obtuse triangles and right triangles also have at least two acute angles. They are called obtuse triangles and right triangles because by definition they are triangles with ONE obtuse angle and ONE right angle. So therefore they both have 2 acute angles. Also for an acute triangle, it would have 3 acute angles.


Triangle with all angles less than ninety?

In plane geometry, all triangles have the sum of the angles to be 180 degrees. So There are many triangles with all the angles less than 90. ( if one angle is more than 90 degrees, then its called 'obtuse' , if all the angles are less than 90, then its called 'Acute' ). Two types of triangles with angles less than 90 degrees are Equalaterial and Isocoles. ( Equalaterial have two equal angles, Isocoles have three equal angles, all 60 degress ). You can think in terms of sets: The subset of Triangles is Acute, The subset of Acute Triangles is Equalateral, The subset of Equalateral Triangles is Isocoles. {Triangles{Obtuse|Acute{Equlaterial{Isocoles


Are all equilateral triangles acute triangles?

Yes all equilateral triangles are acute triangles, but not all acute triangle are equilateral triangles.


How are acute and obtuse triangles the same?

Similarities between these and all triangles are:They all have 3 sides and 3 angles. The sum of the three angles adds up to 180°.An acute angle is less than 90 degrees. An acute triangle has all three sides are acute.An obtuse angle is more than 90 degrees. An obtuse triangle has one angle which is obtuse, and because of the 180° rule above, the other two angles will be acute.So all triangles will have at least two acute angles.


Can scalene triangles be acute or obtuse?

A scalene triangle can have 1 obtuse angle and 2 different acute angles or it can have 3 different acute angles providing that the 3 angles in both scalene triangles add up to 180 degrees.

Related questions

Which shapes have acute angles?

All triangles have at least two acute angles. Acute triangles have three. Rhomboids also have two acute angles.


What is the least number of angles an acute triangle can have?

All acute triangles have 3 interior angles and 3 exterior angles. This is true for all triangles.


Are all acute triangles equilateral triangles?

No, but all equilateral triangles are acute. Acute: All angles of the triangle are less than 90 degrees. Equilateral: All angles of the triangle are 60 degrees.


What types of triangles have at least two acute angles?

All triangles need at least two acute angles


Do all acute triangles have only one acute angle?

No. All triangles MUST have at least two acute angles.


Do all triangles have an acute angle?

All triangles have at least 2 acute angles. All 3 angles of a triangle will equal 180 degrees.


Do all triangles have two acute angles?

INCORRECT: No because there is a obtuse triangle and a right triangleCORRECT ANSWERYes all triangles have at least two acute angles. Obtuse triangles and right triangles also have at least two acute angles. They are called obtuse triangles and right triangles because by definition they are triangles with ONE obtuse angle and ONE right angle. So therefore they both have 2 acute angles. Also for an acute triangle, it would have 3 acute angles.


Do triangles have at least one right angle?

Triangles can be classified by their sides or their angles. When classifying them by their angles, triangles are called: acute triangles - all three angles are acute (less than 90º) right triangles - one right angle (90º) and two acute angles obtuse triangles - one obtuse angle (larger than 90º) and two acute angles


Which triangles are acute triangles?

An acute triangle has all three angles less than 90 degrees.


How are acute and right triangles the same?

Acute triangles have angles less than 90 degrees. Right triangles have 90 degree angles.


Do all triangles have at least to acute angles?

Yes.


Do all right triangles have acute angles?

All right angle triangles have a 90 degree angle and two acute angles that add up to 90 degrees