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The
symbol means "triangle".
SDE means "Triangle SDE".
In the Triangle on the Left
1) the sides are AC, BC and AB.2) the angles are
BAC,
ACB and
ABC
ABC is how we write "Triangle ABC" which is very different from
ABC which means "angle ABC". (Be careful that you use the right mathematical symbol!)
Practice Identifying sides & angles|Properties of Triangles
| Try the Interactive Triangle below: Click any point then drag it around. The sides and angles of the interactive triangle will adjust accordingly. You can also change the scale of the coordinate system below by using the Scale feature. Full sized interactive triangle | Worksheet |
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Triangle's Parts
sides: JK,KL and LJ
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| Identify the angles opposite the following sides: Opposite Angles
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Practice Problem Two
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Identify the sides opposite the following angles: Opposite Sides
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Practice Problem One
What is the m |
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Answer
m m |
Practice Problem Two
| A triangle's angles are |
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Measure of Angle
m |
In any triangle, the largest interior angle is opposite the largest side; the smallest interior angle is opposite the smallest side and, not surprisingly, the middle-sized interior angle is opposite the middle-sized side.
To explore the truth of the statements you can use Math Warehouse's interactive triangle, which allows you to drag around the different sides of a triangle and explore the relationships betwen the measures of angles and sides. No matter how you position the three sides of the triangle, you will find that the statements in the paragraph above hold true.(All right, the isosceles and equilateral triangle are exceptions due to the fact that they don't have a single smallest side or, in the case of the equilateral triangle, even a largest side. Nonetheless, the principle stated above still holds true. !)
Practice Problem One
The exterior angle is supplemental to the adjoining interior angle. Notice:
ABC =46° and the exterior angle is 134°.