Lines that meet at right angles are described as perpendicular to each other. Another word that describes lines that meet at right angles is orthogonal.
Continue ReadingIn two-dimensional plane geometry, whether or not two lines are perpendicular is determined by taking the product of the slopes. If the two lines are perpendicular, the product of the slopes is -1. For instance, a line with slope 5 is perpendicular to any line with slope -1/5. Any vertical line is defined as perpendicular to any horizontal line. This rule is necessary because the slope of a vertical line is undefined, and the slope of a horizontal line is zero.
Learn more about GeometryThe base angle theorem says if two sides of a triangle are congruent, then the angles opposite those sides must also be congruent. The converse is also true. If two angles of a triangle are congruent, then the opposite sides must be also be congruent.
Full Answer >Two angles that share a common side and a common vertex, but have no common interior points are called adjacent angles, often abbreviated as "adj." Adjacent angles lie side by side to each other. Their shared common arm is also called a ray or an edge.
Full Answer >The interior of a pentagon has five angles totaling 540 degrees. In a regular pentagon – a polygon with five congruent sides and five congruent angles – each angle is 108 degrees. Each exterior angle of a regular pentagon is 72 degrees.
Full Answer >According to the University of Washington math department, a regular pentagon has five obtuse angles. The sum of all angles for a regular pentagon is 540 degrees, making each angle 108 degrees. Any angle over 90 degrees is obtuse.
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