Construction of Orthocentre of a Triangle
is the point of concurrency of the altitudes of a triangle. Usually it is denoted
Objective To construct a perpendicular to a line
segment from an external point using paper folding.
Procedure Draw a line segment AB and mark
an external point P. Move B along BA till the fold passes through
P and crease it along that line. The crease thus formed is the perpendicular
to AB through the external point P.
Objective To locate the Orthocentre of a triangle
using paper folding.
Procedure Using the above Activity with any two
vertices of the triangle as external points, construct the perpendiculars to opposite
sides. The point of intersection of the perpendiculars is the Orthocentre of the
Construct ΔPQR whose sides are PQ = 6 cm ∠Q = 600 and QR
= 7 cm and locate its Orthocentre.
Step 1 Draw the ΔPQR with the given measurements.
altitudes from any two vertices (say) R and P, to their opposite sides
PQ and QR respectively.
The point of intersection of the altitude H is the Orthocentre of the given ΔPQR.
Where do the Orthocentre lie in the given triangles.