Basic Geometrical Ideas
Draw a rough sketch of a triangle ABC. Mark a point P in its interior and a point Q in its exterior. Is the point A in its exterior or in its interior?
Rough sketch of a ∠ABC as shown.
Points P and Q are marked in the interior and exterior of ∆ABC.
Point A lies on the ∆ABC.
(a) Identify three triangles in the figure.
(b) Write the names of seven angles.
(c) Write the names of six line segments.
(d) Which two triangles have ZB as common?
(a) Three triangles are identified in the figure as ∆ ABC, ∆ ABD and ∆ ACD.
(b) The names of seven angles are ∠BAD, ∠BAC, ∠CAD, ∠ABD, ∠ACD, ∠ADC and ∠ADB.
(c) The names of six line segments are AB, BD, DC, CA, BC and AD.
(d) ∆ ABC and ∆ ABD have ∠B as common.