Selina solutions

Selina solutions

Selina solutions

Grade 7

CHAPTERS

3. Fractions (Including Problems)

4. Decimal Fractions (Decimals)

5. Exponents (including Laws of Exponents)

6. Ratio and Proportion (Including Sharing in a Ratio)

7. Unitary Method (including Time and Work)

11. Fundamental Concepts (Including Fundamental Operations)

12. Simple Linear Equations (Including Word Problems)

13. Set Concepts (Some Simple Divisions by Vedic Method)

14. Lines and Angles (Including Construction of angles)

17. Symmetry (Including Reflection and Rotation)

18. Recognition of Solids (Representing 3-D in 2-D)

Q1) Using ruler and compasses, construct the following angles :

(i)30°

(ii)15°

(iii) 75°

(iv) 180°

(v) 165°

(vi) 22.5°

(vii) 37.5°

(viii) 67.5°

Solution:

(i) 30°

Steps of Construction :

Draw a line segment BC.

With centre B and a suitable radius draw an arc meeting BC at P.

With centre P and with same radius cut off the arc at Q.

Now with centre P and Q draw two arcs intersecting each other at R

Join BR and produce it to A, forming ZABC

= 30°

(ii) (15°)

Steps of Construction:

Draw a line segment BC.

With centre B and a suitable radius draw an arc meeting BC at P.

With centre P and with same radius cut off the arc at Q.

Taking P and Q as curves, draw two arcs intersecting each other at D and join BD.

With centre P and R, draw two more arcs intersecting each other at S.

Join BS and produce it to A.

Then ∠ABC = 15°.

(iii) 75°

Steps of Construction :

Draw a line segment BC.

With centre B and a suitable radius draw an arc and cut off PQ, then QR of the same radius.

With centre Q and R, draw two arcs intersecting each other at S.

Join SB.

With centre Q and D draw two arcs intersecting each other at T.

Join BT and produce it to A.

Then ∠ABC = 75°.

(iv) 180°

Steps of Construction :

Draw a line segment BC.

With centre B and some suitable radius draw arc meeting BC at P.

With centre P and with same radius cut of arcs PQ, QR and then RS.

Join BS and produce it to A.

Then ∠ABC = 180°.

(v) 165°

Steps of Construction :

Draw a line segment BC.

With centre B and some suitable radius draw an arc meeting BC at P.

With centre P and same radius cut off arcs PQ, QR and then RS.

Join SB

With centres R and S, draw two arcs intersecting each other at M.

With centre T and S draw two arcs intersecting each other at L.

Join BL and produce it to A. Then ∠ABC = 165°

(vi) 22.5°

Steps of Construction :

Draw a line segment BC.

With centre B and some suitable radius, draw an arc meeting BC at P.

With centre P and some radius, cut off arcs PQ.

Bisect arc PQ at R and join BR.

Bisect arc QR at S and join BS.

Now bisect arc PR at T.

Join BT and produce it to A.

(vii) 37.5°

Steps of Construction :

Draw a line segment BC.

With centre B and some suitable radius, draw an arc meeting BC at P.

With centre P and same radius cut off arcs PQ and QR.

Now bisect arc QR at S and again bisect arc QS at T.

Bisect arc PT at K.

Join BK and produce it to A.

(viii) 67.5°

Steps of Construction :

Draw a line segment BC.

With centre B and some suitable radius, draw an arc meeting BC at P.

With centre P and with same radius, cut arcs PQ and then QR.

Bisect arc QR at K and again bisect arc QK at S.

Bisect again arc SQ at T.

Join BT and produce it to A.

Still have questions? Our expert teachers can help you out

Book a free class nowFractions (Including Problems)

Exponents (including Laws of Exponents)

Ratio and Proportion (Including Sharing in a Ratio)

Unitary Method (including Time and Work)

Fundamental Concepts (Including Fundamental Operations)

Simple Linear Equations (Including Word Problems)

Set Concepts (Some Simple Divisions by Vedic Method)

Lines and Angles (Including Construction of angles)

Symmetry (Including Reflection and Rotation)

Recognition of Solids (Representing 3-D in 2-D)

Q1) Using ruler and compasses, construct the following angles :

(i)30°

(ii)15°

(iii) 75°

(iv) 180°

(v) 165°

(vi) 22.5°

(vii) 37.5°

(viii) 67.5°

Solution:

(i) 30°

Steps of Construction :

Draw a line segment BC.

With centre B and a suitable radius draw an arc meeting BC at P.

With centre P and with same radius cut off the arc at Q.

Now with centre P and Q draw two arcs intersecting each other at R

Join BR and produce it to A, forming ZABC

= 30°

(ii) (15°)

Steps of Construction:

Draw a line segment BC.

With centre B and a suitable radius draw an arc meeting BC at P.

With centre P and with same radius cut off the arc at Q.

Taking P and Q as curves, draw two arcs intersecting each other at D and join BD.

With centre P and R, draw two more arcs intersecting each other at S.

Join BS and produce it to A.

Then ∠ABC = 15°.

(iii) 75°

Steps of Construction :

Draw a line segment BC.

With centre B and a suitable radius draw an arc and cut off PQ, then QR of the same radius.

With centre Q and R, draw two arcs intersecting each other at S.

Join SB.

With centre Q and D draw two arcs intersecting each other at T.

Join BT and produce it to A.

Then ∠ABC = 75°.

(iv) 180°

Steps of Construction :

Draw a line segment BC.

With centre B and some suitable radius draw arc meeting BC at P.

With centre P and with same radius cut of arcs PQ, QR and then RS.

Join BS and produce it to A.

Then ∠ABC = 180°.

(v) 165°

Steps of Construction :

Draw a line segment BC.

With centre B and some suitable radius draw an arc meeting BC at P.

With centre P and same radius cut off arcs PQ, QR and then RS.

Join SB

With centres R and S, draw two arcs intersecting each other at M.

With centre T and S draw two arcs intersecting each other at L.

Join BL and produce it to A. Then ∠ABC = 165°

(vi) 22.5°

Steps of Construction :

Draw a line segment BC.

With centre B and some suitable radius, draw an arc meeting BC at P.

With centre P and some radius, cut off arcs PQ.

Bisect arc PQ at R and join BR.

Bisect arc QR at S and join BS.

Now bisect arc PR at T.

Join BT and produce it to A.

(vii) 37.5°

Steps of Construction :

Draw a line segment BC.

With centre B and some suitable radius, draw an arc meeting BC at P.

With centre P and same radius cut off arcs PQ and QR.

Now bisect arc QR at S and again bisect arc QS at T.

Bisect arc PT at K.

Join BK and produce it to A.

(viii) 67.5°

Steps of Construction :

Draw a line segment BC.

With centre B and some suitable radius, draw an arc meeting BC at P.

With centre P and with same radius, cut arcs PQ and then QR.

Bisect arc QR at K and again bisect arc QK at S.

Bisect again arc SQ at T.

Join BT and produce it to A.

Still have questions? Our expert teachers can help you out

Book a free class nowLido

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