圆复习课（Round review lesson）.docVIP

圆复习课（Round review lesson） T: then how long can you figure out the longest route for Xiao Mings treasure? Student: () what method is used to produce the formula: C= PI, D, C=2, PI, R? Teacher: suppose Xiao Ming wants to find the treasure within 3 meters from where Xiao Ming is How big is the maximum range? What is the calculation of the circle? Formula: S= PI R2 It seems that you understand the features of the circle clearly For Xiao Ming found the location of the treasure But Xiao Ming must accept the challenge Successfully get points in order to get treasure Would you like to help him pass through? Students: 3., draw round, feel the circle Challenge the first hurdle: draw a circle with your compasses Can you draw circles? Students draw Inspection tour Collection (display) One big, one small, two circles Why does that happen?  Summary: location of the center of the circle Radius determines the size of the circle Teacher: just through the report The students have a more profound impression of the circle Smooth through the first pass Now lets continue the checkpoints OK or not? Challenge second hurdle: the following statement, right? Incorrect explanation 1, the circle is an axisymmetric figure It has only one axis of symmetry, and its diameter () 2. All radii are equal All diameters are equal () The 3.14 is 3, the value of Pi Pi () 4 、 circle with 2cm radius The circumference is equal to the area () 5, the radius of a circle is enlarged by 3 times The circumference of the circle is enlarged 3 times as well () 6, the radius of a circle is enlarged by 4 times It also expanded in size by 8 times () 7. The center of the circle determines the location of the circle The size of the radius determines the size of the circle area () 8. The circumference of a circle is 2 times the radius of it () You are too fierce Through the collective power to help Xiao Ming second Third, but many organs You chose to give up Or continue to pass through it? Article 3: according to the requi