Adjacent angles are one of the earliest and most important concepts to learn in basic geometry, as they have applications in further subjects like trigonometry, physics, and engineering. Effective ...

Obtuse angles (greater than 90° and less than 180°). Using the combination of different types of angles, identify the triangle. An acute-angled triangle has three angles that are all less than 90°.

A triangle is a polygon. It is a closed 3-sided shape made up of straight lines. The ‘tri-’ part of the word triangle means three. A triangle has 3 sides and 3 angles.