We-Math

3stpes_1

testmini

Properties and Understanding of Squares

As shown in the figure, a circle is drawn with vertex C of the square as the center. What is the measure of the central angle ∠ECF? ( )°

A. 45; B. 60; C. 72; D. 90; E. No correct answer

D

<image/binary>

3steps_1

1081

Properties and Understanding of Squares: 1. A square is a special type of parallelogram. A parallelogram with one pair of adjacent sides equal and one right angle is called a square, also known as a regular quadrilateral. 2. Both pairs of opposite sides are parallel; all four sides are equal; adjacent sides are perpendicular to each other. 3. All four angles are 90°, and the sum of the interior angles is 360°. 4. The diagonals are perpendicular to each other; the diagonals are equal in length and bisect each other; each diagonal bisects a pair of opposite angles. 5. A square is both a centrall …

3stpes_1

testmini

Circumference of Circles

As shown in the figure, a circle is drawn with vertex C of the square as the center, and the radius of the circle is as shown in the figure. The circumference of this circle is () cm. (Use π = 3.14)

A. 50.24; B. 25.12; C. 12.56; D. 6.28; E. No correct answer

B

<image/binary>

3steps_2

1246

Circumference of Circles: 1. A line segment passing through the center of a circle with both endpoints on the circle is called the diameter, usually denoted by the letter d. A line segment connecting the center of the circle to any point on the circle is called the radius, usually denoted by the letter r. 2. The circumference of a circle = diameter × pi (C = πd) or the circumference of a circle = 2 × radius × pi (C = 2πr). 3. The circumference of a semicircle can be calculated using the formula C = πr + 2r. 4. In the same circle or congruent circles, there are an infinite number of radii and a …