Identify which type of triangle appears in the drawing:
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Identify which type of triangle appears in the drawing:
Note that the sum of angles in a triangle equals 180 degrees.
Let's calculate alpha in the following way:
Let's divide both sides by 1.5:
Now we can calculate the remaining angle in the triangle:
So in the triangle we have 3 angles: 60, 80, 40
All of them are less than 90 degrees, therefore all angles are acute angles and the triangle is an acute triangle.
Acute triangle
In a right triangle, the side opposite the right angle is called....?
The notation means one angle is half the size of another angle. In this triangle, one angle equals α and another equals α divided by 2.
A single angle doesn't determine triangle type! You need all three angles. Even though 60° is acute, the other angles could be obtuse (>90°) or right (=90°).
Acute: All angles < 90°
Right: One angle = 90°
Obtuse: One angle > 90°
Remember: only one classification applies to each triangle!
First subtract 60 from both sides:
Then divide by 1.5 (or multiply by ):
No! If two angles were each greater than 90°, their sum would exceed 180° - but that's already the total for all three angles combined. Only one obtuse angle is possible per triangle.
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