Lines and Angles Sums for Class 6 — Free CBSE Worksheet PDF with Answers

Every shape you will ever study in maths is made of lines and angles. A triangle has 3 line segments and 3 angles. A rectangle has 4 of each. Even circles involve angles when you study arcs and sectors later. The Class 6 CBSE Lines and Angles chapter (Ganita Prakash Chapter 2) teaches you to see geometry precisely — the difference between a line, a ray, and a segment, and how to measure and classify angles.

A line extends infinitely in both directions and has no endpoints. A ray has one endpoint and extends forever in one direction. A line segment has two endpoints and a definite length. The notation matters: $\overleftrightarrow{AB}$ is a line, $\overrightarrow{AB}$ is a ray, and $\overline{AB}$ is a segment. CBSE exam questions test this precision.

This worksheet has 60 questions split across three levels. Level 1 covers identification of lines, rays, and segments, classifying angles, and reading a protractor. Level 2 builds fluency with angle measurement, drawing angles, and finding missing angles. Level 3 tackles angle relationships, perpendicular and parallel lines, and multi-step reasoning.

An acute angle is less than $90°$. A right angle is exactly $90°$. An obtuse angle is greater than $90°$ but less than $180°$. A straight angle is exactly $180°$ (a flat line). A reflex angle is greater than $180°$ but less than $360°$. A complete angle is exactly $360°$ — a full turn.

Class 6 students often confuse reflex angles with regular ones. If an angle looks 'open' beyond a straight line, it is reflex. The reflex angle = $360°$ minus the smaller angle measured on the other side. So if a protractor reads $130°$ on the inside, the reflex angle on the outside is $360° - 130° = 230°$.

Two angles are complementary if they add up to $90°$. So $37°$ and $53°$ are complementary. Two angles are supplementary if they add up to $180°$. So $115°$ and $65°$ are supplementary. A useful memory trick: C comes before S in the alphabet, and 90 comes before 180.

Angles on a straight line add up to $180°$ (because a straight line is a $180°$ angle). If three angles $x°$, $2x°$, and $3x°$ lie on a straight line, then $x + 2x + 3x = 180$, giving $6x = 180$, so $x = 30°$. The three angles are $30°$, $60°$, and $90°$. When two lines cross, the four angles formed are two pairs of vertically opposite angles, and vertically opposite angles are always equal.

Place the centre point of the protractor on the vertex of the angle. Align one arm of the angle with the $0°$ line of the protractor. Read the scale where the other arm crosses the protractor. The trick is: protractors have two scales, an inner and an outer scale. Always check which scale starts at $0°$ along your reference arm — that is the scale you should read.

When drawing an angle of, say, $125°$, mark the vertex, draw one arm, place the protractor with that arm along $0°$, find $125°$ on the correct scale, mark a dot, and join. $125°$ is between $90°$ and $180°$, so it is an obtuse angle.