Angles and Lines: Right, Acute, Obtuse & Parallel
Print 4th grade geometry worksheets identifying acute, right, and obtuse angles, plus parallel, perpendicular, and intersecting lines with answer keys. Aligned with Common Core standards CCSS 4.G.A.1 and CCSS 4.MD.C.5.
Worksheet version 1 of 12. Each version generates different angles and lines with an exact matching answer key.
1. Classify this angle: acute, right, obtuse, or straight.
Angle type: ____________________
2. Classify these lines: parallel, perpendicular, or intersecting.
Relationship: ____________________
3. Estimate the measure of this angle: about 30°, 90°, or 140°?
Best estimate: ____________________
4. Look at the marked corner of this triangle. What kind of angle is it?
Marked angle: ____________________
5. Two angles form a 90° right angle. Angle A is 35°. Find angle B.
Angle B = ________ degrees
6. In a rectangle, are opposite sides parallel or perpendicular?
Opposite sides are: ____________________
About Angles and Lines in 4th Grade
An angle is formed by two rays sharing a common endpoint called the vertex. In 4th grade geometry:
- Right angle: Exactly 90°, forming a square corner.
- Acute angle: Less than 90°, sharper than a square corner.
- Obtuse angle: Greater than 90° and less than 180°, wider than a square corner.
- Straight angle: Exactly 180°, forming a straight line.
For lines: parallel lines never meet, while perpendicular lines intersect at right angles (90°).
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