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Line of Symmetry

Class 6 Maths · Chapter 9: Symmetry · NCERT Ganita Prakash section 9.1

Seekho

Meher kaagaz ke ek hisse par rang ki boond girati hai, kaagaz ko beech se modti hai aur dabaati hai. Kholne par titli ban jaati hai! Dono hisse ek doosre ke mirror image hain.

Kisi shape mein symmetry tab hai jab ek line use do aise hisson mein baante jo modne par bilkul milte hain. Wo mod ki line line of symmetry (ya mirror line) hai. Uspar modo, to ek hissa bilkul doosre par aata hai.

Kuch shapes mein ek se zyada hoti hain. Square mein 4: upar-neeche, aar-paar, aur do diagonals. Rectangle mein sirf 2. Rectangle ko diagonal par modkar dekho: hisse ek doosre par nahi aate!

Regular polygon (saari bhujaayein barabar aur saare kon barabar) mein utni lines of symmetry hoti hain jitni bhujaayein: samabahu triangle mein 3, regular pentagon mein 5, regular hexagon mein 6.

Aur kuch shapes mein koi line of symmetry nahi, jaise sab alag bhujaon wala triangle, ya parallelogram (tirchha rectangle). Koi mod hisson ko nahi milaata.

Aas-paas symmetry dhoondo: letters A, H, M, T, U; darwaze ki rangoli; patta; mandir ya masjid ka saamne ka hissa. Mod-kar-kaate kaagaz ke chains aur mude kaagaz mein kiye ched bhi symmetric nikalte hain.

Explore: har picture aise poori karo ki dashed line, line of symmetry ho.

  1. Neele squares ko line ke paar mirror karo.
  2. Ab mirror line aar-paar hai.
  3. Do mirror lines! Picture ko dono ke liye symmetric banao.

Explore: lines of symmetry par tap karo.

  1. Square ki saari lines of symmetry par tap karo.
  2. Ab rectangle.
  3. Aur regular hexagon.

Yaad rakho

  • Line of symmetry shape ko do aise hisson mein baant-ti hai jo modne par bilkul milte hain.
  • Square 4, rectangle 2, n bhujaon wala regular polygon: n. Kuch mein ek bhi nahi.

Quick check

Rectangle (jo square nahi) ki kitni lines of symmetry hain?

  1. 2
  2. 4
  3. 1
  4. 0
Answer

2. Upar-neeche aur aar-paar. Rectangle ke diagonals line of symmetry nahi hain.

Socho

Gauri square kaagaz ko aadha modti hai, phir doosri taraf se phir aadha. Wo ek kone ke paas ek ched karti hai aur kholti hai. Kitne ched hain, aur kahan?

Ek answer

4 ched. Har mod unhe double karta hai, aur dono mod ki lines, lines of symmetry hain, isliye ched chaaron chauthaiyon mein ek jaisi jagah par hote hain.

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.