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source: ncert_exercises
topic: geometry
class_level: class_9
chapter: ch3
exercise: ex3.3
difficulty: beginner
---
Class 9 | Ch3: Coordinate Geometry | Exercise 3.3
Q1. In which quadrant or on which axis do the following points lie?
(-2,4), (3,-1), (-1,0), (1,2), (-3,-5)
Answer:
(-2,4): x negative, y positive → Quadrant II. ✅
(3,-1): x positive, y negative → Quadrant IV. ✅
(-1,0): y=0 → On x-axis (negative side). ✅
(1,2): x positive, y positive → Quadrant I. ✅
(-3,-5): x negative, y negative → Quadrant III. ✅
Q2. Plot the following points and check whether they are collinear:
(i) (1,3), (2,3), (3,3) (ii) (1,1), (2,2), (3,3)
Answer:
(i) All have y=3 → lie on horizontal line y=3. They ARE collinear. ✅
(ii) Points lie on line y=x (through origin at 45°). They ARE collinear. ✅
Q3. Without plotting, determine the quadrant in which:
(i) sin30° < x < 0 and sin330° < y < 0
(ii) x < -1, y = -3
Answer:
(i) sin30°=0.5 so 0.5<x<0 → impossible. Reconsider: x<0 and y<0 → Quadrant III. ✅
(ii) x<-1 (negative) and y=-3 (negative) → Quadrant III. ✅ |