1. The arc length of the sector is a, the radius is r, the sector area is 2, and the concentric angle of the sector is 150 degrees. Then the area of the sector is equal to the area of the circle where the sector is located 3. If the radius of circle O is 4cm and one of the arcs is 2cm long, what is the central angle of the arc

1. If you know the degree of the central angle of the circle, then the arc length and radius of the sector can no longer be used. The area of the sector is equal to 150 / 360 of the area of the circle, that is, 15 / 36
3. If the radius is 4, then the diameter is 8 and the circumference is 8 π. Since the arc length is 2 π, then it is 1 / 4 of the circumference, so the center angle of the circle should be 1 / 4 of 360 degrees, that is 90 degrees

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1. The sum of the side length of a square and the width of a rectangle is 20 cm, the perimeter of a square is one and one third of the perimeter of a rectangle, and the width of a rectangle is 4 / 5 of the length. How much is the area of the square and rectangle and the fact How much is the area sum of square and rectangle?
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4. According to 123456789 * 9 = 1111111101, make the following formula answer 123456789*18=?123456789*36=?123456789*54=?123456789*72=? 123456789*27=?123456789*45=?123456789*63=?123456789*81=?
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