Page 69 - Key Stage 3 Geometry
P. 69
9. To measure the reflex angle,
measure the external angle and
o
subtract 360 , enter this value in
the table.
10. Add up all the angles and
o
they should come to 720 .
4.5 Heptagon
The sum of the internal angles of
o
a heptagon is 900 . In this
exercise you are going to draw an
irregular heptagon and measure
all seven of its internal angles.
1. Draw a horizontal line 5 cm long.
2. From the right of this line draw a second line 4
cm long with an obtuse angle.
3. From the end of the second line draw a third line
of length 4 cm with an obtuse angle.
4. From the end of the third line, draw a fourth line
of length 2 cm with an acute angle.
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