Algebraic Expressions & Formulae

Names of angles
acute angle (<90^\circ)
right angle (90^\circ)
obtuse angle (90^\circ<\theta<180^\circ)
reflex angle (>180^\circ)
Types of angles
1. \angle on a st. line
2. \angle at a pt.
3. vert. opp. \angle
4. alt. \angle
5. corr. \angle
6. int. \angle
Types of polygons

    \[\begin{array}{|c|c|} \hline \textbf{No. of sides}& \textbf{Polygons} \\\hline \text{3} & \text{triangle} \\\hline \text{4} & \text{quadrilateral} \\\hline \text{5} & \textbf{pent}\text{agon} \\\hline \text{6} & \textbf{hex}\text{agon} \\\hline \text{7} & \textbf{hept}\text{agon} \\\hline \text{8} & \textbf{oct}\text{agon} \\\hline \text{9} & \textbf{non}\text{agon} \\\hline \text{10} & \textbf{dec}\text{agon} \\\hline \end{array}\]

Sum of interior & exterior angles
Sum of interior angles =(n-2)\times180^\circ
Sum of exterior angles =360^\circ