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CLIL WORKSHEETS
13 MATHS
Geometry – Triangles
1
Match the triangles with their descriptions.
1 Acute-angled triangles: all angles are less
than 90° (acute)
2 Isosceles triangles: 2 sides are equal and the
angles opposite the equal sides are equal.
3 Obtuse-angled triangles: one of the angles
of the triangle is greater than 90° (obtuse).
The longest side is opposite the largest angle.
4 Scalene triangles: no sides are equal and all
angles are different
5 Right-angled triangle: one of the three
angles of the triangle is a right-angle
6 Equilateral triangles: all sides are equal
and all angles are equal to 60°
2
Complete the following sentence.
The sum of the three angles in a triangle is always
equal to __________ .
3
Answer the questions.
1 A right-angled triangle has another angle of 38°.
What size is the third angle?
2 A triangle has one obtuse angle of 107° and an
acute angle of 45°. What kind of angle will the
third angle be and how many degrees?
3 An equilateral triangle has one side of 45cm.
What size will the angle opposite that side be?
4
Calculate the size of angle BAC in the triangle.
PORTFOLIO PROJECT
Write similar triangle exercises and see if
your partner can solve them. Write the
solutions.
Headway Digital Fourth Edition Pre-Intermediate Photocopiable © Oxford University Press 2012
Headway Digital
Pre-Intermediate
FOURTH EDITION