metadata
source: ncert
topic: geometry
class_level: class_7
chapter: ch5
difficulty: beginner
Class 7 | Ch5: Lines and Angles Complementary=90° total. Supplementary=180° total. Linear pair=180°. Vertically opposite=EQUAL. Parallel lines + transversal: 8 angles formed. Corresponding angles: same position=EQUAL (F-shape). Alternate interior angles: between lines, alternate sides=EQUAL (Z-shape). Co-interior angles: between lines, same side=SUPPLEMENTARY=180° (C-shape). Alternate exterior angles: outside, alternate sides=EQUAL. Converse: if corresponding/alternate angles equal → lines parallel. Example: angle=65°. Corresponding=65°. Alternate interior=65°. Co-interior=115°. Two supplementary angles, one=3 times other: x+3x=180 → x=45°, angles=45° and 135°. Co-interior angles SUPPLEMENTARY not equal. Vertically opposite ALWAYS equal.