What is the name of a triangle with a 90 degree angle?
The right triangle has one 90 degree angle and two acute (< 90 degree) angles. Since the sum of the angles of a triangle is always 180 degrees The two sides of the triangle that are by the right angle are called the legs and the side opposite of the right angle is called the hypotenuse.
Perpendicular lines. Two lines that intersect and form right angles are called perpendicular lines. The symbol ⊥ is used to denote perpendicular lines. In Figure , line l ⊥ line m.
- The rows resemble line segments. A line is a straight set of points that extend in opposite directions without ending. A ray is a part of a line that has one endpoint and extends in one direction without ending. A line segment is a part of a line between two endpoints.
- Table of symbols in geometry:
Symbol Symbol Name Meaning / definition | | parallel parallel lines ≅ congruent to equivalence of geometric shapes and size ~ similarity same shapes, not same size Δ triangle triangle shape
- Parallel lines never meet, and perpendicular lines intersect at a right angle. and do not intersect in this image, but if you imagine extending both lines, they will intersect soon. So, they are neither parallel nor perpendicular.
A triangle is scalene if all of its three sides are different (in which case, the three angles are also different). If two of its sides are equal, a triangle is called isosceles. A triangle with all three equal sides is called equilateral.
- Find the value of x and then classify the triangle by its angles. The sum of the angle measures in a triangle is 180 degrees. The triangle has one obtuse angle, so it is an obtuse triangle. Find the value of x and then classify the triangle by its angles.
- An acute triangle is a triangle with all three angles acute (less than 90°). An obtuse triangle is one with one obtuse angle (greater than 90°) and two acute angles. Since a triangle's angles must sum to 180°, no triangle can have more than one obtuse angle.
- An obtuse triangle is a triangle in which one of the angles is an obtuse angle. (Obviously, only a single angle in a triangle can be obtuse or it wouldn't be a triangle.) A triangle must be either obtuse, acute, or right.
Updated: 2nd October 2019