Chapter 2: Lines aur Angles
Tum jo bhi shape banate ho, wo kuch aasaan hisson se banti hai: points, lines, line segments, rays aur angles. Is chapter mein hum in hisson ke naam seekhenge, angles ko degrees mein milaayenge aur naapenge, aur protractor se koi bhi angle banayenge.
Is chapter mein tum
- points, line segments, lines aur rays mein farq karna aur unke naam rakhna
- angles ke naam rakhna aur unka vertex aur arms dhoondhna
- angles ki tulna unke ghumaav se karna
- protractor se angles naapna aur banana
- angles ko acute, right, obtuse, straight aur reflex mein baantna
Topics
- Point, Line Segment, Line aur Ray NCERT 2.1–2.4
Point: theek jagah, capital letter se naam.
- Angle NCERT 2.5
Ek hi point (vertex) se shuru hone wali do rays angle banati hain. Rays uski arms hain.
- Angles ki tulna aur Rotating Arms NCERT 2.6–2.7
Angles ki tulna ek ko doosre par vertex milaakar rakhkar karo (superimposition).
- Khaas tarah ke Angles NCERT 2.8
Poora chakkar: poora ghoomna. Straight angle: aadha chakkar, arms ek seedhi line mein.
- Angles naapna NCERT 2.9
1 poora chakkar = 360°. Straight angle = 180°. Right angle = 90°.
- Angles banana NCERT 2.10
Base arm kheencho, protractor ka centre vertex par aur base 0 par, angle tak gino aur point lagao, phir jodo.
- Angles ke types aur unke naap NCERT 2.11
Acute: 0°–90°. Right: 90°. Obtuse: 90°–180°. Straight: 180°. Reflex: 180°–360°.
Key words
- Point
- ek theek jagah, capital letter se naam
- Line segment
- do points ke beech sabse chhota raasta; do end points
- Line
- dono taraf hamesha chalti hai
- Ray
- ek point se shuru, ek taraf hamesha
- Angle
- common starting point wali do rays
- Vertex
- angle ki arms ka common starting point
- Degree (°)
- poore chakkar ke 360 barabar hisson mein se ek
- Protractor
- angles naapne aur banane ka auzaar
- Perpendicular
- right angle par milne wali lines
- Angle bisector
- angle ko do barabar hisson mein kaatne wali line
Summary
- Point ek pakki jagah batata hai. Uska naam capital letter se rakhte hain.
- Line segment do points ko jodta hai aur dono par rukta hai. Line dono taraf hamesha chalti hai. Ray ek point se shuru hokar ek taraf hamesha chalti hai.
- Ek hi point se nikli do rays angle banati hain. Saajha point vertex hai aur rays arms hain.
- Angle kitna bada hai ye is par depend karta hai ki ek arm doosre tak pahunchne ke liye kitna ghoomta hai, arms ki lambai par nahi.
- Hum angles ko protractor se degrees mein naapte hain. Poora chakkar 360° hai.
- Angle ke prakaar: acute (90° se kam), right (90°), obtuse (90° aur 180° ke beech), straight (180°) aur reflex (180° se zyada).