Pedagogy of Mathematics (Part II) - Geometry, Geometry, Maths, IX std Maths, Samacheerkalvi maths, II year B.Ed., Pedagogy, Mathematics, Practical Geometry, construction of the centroid of a triangle, centroid, orthocentre of a triangle

1. PEDAGOGY OF
MATHEMATICS – PART II
BY
Dr. I. UMA MAHESWARI
Principal
Peniel Rural College of Education,Vemparali,
Dindigul District
iuma_maheswari@yahoo.co.in

2. Std IX - Ex 4.5

16. Solution:
Steps for construction:
Step 1: Draw the ΔLMN using the given
measurement LM = 7.5 cm, MN = 5cm and LN =
8cm.
Step 2: Construct the perpendicular bisectors of any
two sides LM and MN intersect LM at P and MN at
Q respectively.
Step 3: Draw the median LQ and PN meet at G.
The point G is the centroid of the given ΔLMN.

17. Solution:
Steps for construction:
Step 1: Draw the ΔABC using the given
measurement AB = 4cm and AC = 3 cm and ZA
= 90°.
Step 2: Construct the perpendicular bisectors of
any two sides AB and AC to find the mid-points
P and Q of AB and AC.
Step 3: Draw the medians PC and BQ intersect
at G.
The point G is the centroid of the given ΔABC.

18. Solution:
Steps for construction:
Step 1: Draw the ΔABC using the given
measurement AB = 6cm, AC = 9cm and
∠B =110°.
Step 2: Construct the perpendicular
bisectors of any two sides AB and BC to
find the mid-points P and Q of AB and BC.
Step 3: Draw the medians PC and AQ
intersect at G.
The point G is the centroid of the given
ΔABC.

19. Solution:
Steps for construction:
Step 1 : Draw ΔPQR using the given measurements PQ =
5cm, PR = 6cm and ∠P = 60°.
Step 2 : Construct the perpendicular bisectors of any two
sides PQ and QR to find the mid-points of M and N
respectively.
Step 3 : Draw the median PN and MR and let them meet at G.
The point G is the centroid of the given ΔPQR.

20. Solution:
Steps for construction:
Step 1: Draw the ΔPQR with the given
measurements.
Step 2: Construct altitudes from any two
vertices P and Q to their opposite sides QR
and PR respectively.
Step 3: The point of intersection of the
altitude H is the orthocentre of the given

21. Solution:
Steps for construction:
Step 1: Draw the ΔABC with the given
measurements.
Step 2: Construct altitudes from any two
vertices A and C to their opposite sides BC
and AB respectively.
Step 3: The point of intersection of the
altitude H is the orthocentre of the given
ΔABC.

22. Solution:
Steps for construction:
Step 1: Draw the ΔABC with the given
measurements.
Step 2: Construct altitudes from any two
vertices B and C to their opposite sides AC
and BC respectively.
Step 3: The point of intersection of the
altitude H is the orthocentre of the given
ΔABC.

23. Solution:
Steps for construction:
Step 1: Draw the ΔPQR with the given
measures.
Step 2: Construct altitude from any two
vertices Q and R to their opposite side PR
and PQ respectively.
Step 3: The point of intersection of the
altitude H is the orthocentre of the given