Page 23 - 新思维数学学生用书5 样章

2 2D shape and pattern

Worked example 1

Is this an equilateral, isosceles or

scalene triangle?

• Are all the lengths the same? Measure the lengths of each side.

No, the triangle is not equilateral. • All the sides of an equilateral triangle
• Are two of the lengths the same? are the same length and all the

No, the triangle is not isosceles. angles are the same size.

• Are all the lengths different? • Two sides of an isosceles triangle
Yes. are the same length and two of the

• Compare the three angles of the angles are the same size.
triangle. Are any of the angles the • None of the sides of a scalene triangle

same size? are the same length and none of the

No, the triangle is not equilateral angles are the same size.
or isosceles.

Answer: The triangle is scalene.

Exercise 2.1

1 Which of these triangles are scalene?

A B C

D E

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