题目内容
Many times a reporter needs works that describe how something looks.Then he uses special words.And so it is with mathematics.The words square and rectangle are special words in mathematics.
A square has four sides and four square corners.But all four sides of a square are the same in length.
A rectangle also has four sides and four square corners.Two sides of a rectangle are usually longer than the other two sides.
Two more special words used in mathematics are triangle and circle.A triangle has only three sides and three corners.A triangle is like the top of a roof that comes to a point.The space at any corner.A triangle is like the top of a roof the comes to a point.The space at any corner between two sides in a triangle is called an angle.If all the three sides of a triangle are equal, then all the three angles would be equal too.Such a kind of triangle is called an equilateral triangle.
A circle has no sides at all.It is a closed pane curve(弧线)consisting of all points equally distant from a point within it, called the center.A circle is like the face of a coin.Some times a person says a thing is “circular”.Do you think you know what he means?
In geometry we also have words like cube, sphere, cylinder, cone and so on.They are all three dimensional(三维的).But we are not going to deal with them here.
1.Sometimes a person says that something is circular, he means this something is ______.
[ ]
A.a circle
B.like a circle
C.round in shape
D.curved in shape
2.Which of the following is not necessarily true? A closed plane curve is ______. [ ]
A.a space enclosed by a curved line
B.a curve
C.two-dimensional
D.a circle
3.Which of the following is equilateral?______.
[ ]
A.triangle B.Square
C.Circle D.Rectangle
4.Which of the following does not have an angle of 90 degree?______.
[ ]
A.a right angled triangle
B.A square
C.A rectangle
D.A circle
5.Which of the following statements is true of a curve?______.
[ ]
A.No part of which is straight
B.It changes direction without angle
C.It is always closed
D.It is continuously bending line
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