Tribhuj ke Prakaar

Class 7 Maths · Chapter 7: Teen Kaat'ti Lines ki Kahaani · NCERT Ganita Prakash section 7.5

Seekho

Bhujaon se: equilateral (samabahu) ki saari bhujaayein barabar, isosceles (samadvibahu) ki do barabar, aur scalene (vishambahu) ki teeno alag. To 4, 4, 4 equilateral; 5, 5, 8 isosceles; 4, 5, 6 scalene.

Angles se: right-angled mein ek right angle; obtuse-angled mein ek obtuse angle. Acute-angled mein teeno angles acute. Sirf ek acute kyun nahi? Kyunki har tribhuj mein kam se kam do acute angles hote hi hain!

Tribhuj mein zyaada se zyaada ek right ya obtuse angle: 90° ya zyaada ke do angles hi 180° tak pahunch jaayenge. Samabahu ka har angle 180° ÷ 3 = 60°, to wo hamesha acute-angled. Isosceles right-angled (90°, 45°, 45°) ya obtuse-angled (120°, 30°, 30°) ho sakta hai.

equilateral: 60°, 60°, 60°

Dibbe ki paheli: dibbe ke ek kone mein makdi door ke ulte kone tak jaana chahti hai, sirf satahon par chalkar. Zoya dibbe ko kholkar sapaat karti hai: sabse chhoti raah khule jaal par seedhi line ban jaati hai, kyunki seedha raasta sabse chhota hai, bilkul triangle inequality jaisa.

Explore: angles se sort karo.

Har tribhuj ko angles se sort karo.

Yaad rakho

Bhujaon se: equilateral, isosceles, scalene. Angles se: acute-, right-, obtuse-angled.
Har tribhuj mein kam se kam do acute; zyaada se zyaada ek 90° ya zyaada.

Quick check

Tribhuj ke angles 30°, 60° aur 90°. Kis prakaar ka?

right-angled aur scalene
acute-angled
obtuse-angled
equilateral

Answer

right-angled aur scalene. Ek angle 90°, aur teen alag angles matlab teen alag bhujaayein.

Socho

∠B = 90° aur AC = 5 cm wale kitne alag right tribhuj ABC hain?

Ek answer

Anant. ∠A 0° aur 90° ke beech kuch bhi (phir ∠C = 90° − ∠A), aur har chunaav alag tribhuj deta hai.

Practice

Teen levels (easy, medium, hard) ke naye sawaalon se practice karo, kuch hands-on, hints aur hal ke saath. Topic poora karne ke liye pichhle 5 mein se 4 sahi karo.