A circular mirror with a radius of 5cm has an area of () square cm and a perimeter of () cm emergency

A circular mirror with a radius of 5cm has an area of (78.5) square cm and a perimeter of (31.4) cm

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1. The radius of the outer circle of a ring is 1.5cm, the radius of the inner circle is 1cm, what is the area
2. If the base of isosceles triangle is 5cm and the perimeter is 20cm, then the other two sides are () cm and () cm respectively
3. The perimeter of the triangle with 5cm difference on each side is 120cm. How many cm is the shortest side?
4. If the lengths of the two sides of the triangle are 5cm and 12cm respectively, then the third side is the root of the equation x ^ 2-30x + 221 = 0. What is the circumference of the triangle?
5. The side length of a square is equal to the radius of a circle. It is known that the area of a square is a square cm. 1
6. A cuboid is 14cm long and 10cm wide. If the length and width of the cuboid remain unchanged, the surface area of the cuboid will increase by 144cm square when the height increases by how many centimeters
7. The length, width and height of a cuboid are 11cm, 6cm and 14cm respectively. If the cuboid is reduced by 3cm, the surface area will be reduced by () cm and the volume will be reduced by () cm
8. A cylindrical bucket without cover is made of plastic plate. The diameter of the bottom of the bucket is 60cm and the height is 80cm. How many square meters of plastic plate is needed to make such a bucket?
9. Fill a cylindrical bucket with a diameter of 40 cm and a height of 60 cm full of water into another cylindrical bucket with a radius of 30 cm, and then ask what the water is What's the height? We need to solve the equation of first degree with one variable
10. The circumference of an isosceles triangle is 80 cm, and the length of its waist is twice that of its bottom. How many cm are the waist and bottom of the isosceles triangle
11. In this paper, a 20 cm long wire is used to encircle a rectangle. The functional relationship between the area s (CM & # 178;) and the length x (CM) of the encircled rectangle is obtained, and the value range of the independent variable x is determined
12. Given that the three sides of a triangle are (2x + 1) cm, (X & # 178; + 2) cm, (X & # 178; + 2x + 1) cm, then the perimeter of the triangle is (2x + 1) cm
13. It is known that the perimeter of a triangle is 2x & # 178; cm, and the lengths of its two sides are (2x + 1) cm, (X & # 178; - 2x + 1) cm Given that the perimeter of a triangle is 2x & # 178; cm, and that the lengths of its two sides are (2x + 1) cm, (X & # 178; - 2x + 1) cm, what is the length of the third side of the triangle?
14. The area of the shadow triangle is 15 square centimeters, the area of the trapezoid is 5cm at the top and 9cm at the bottom See the answer (5 + 9) × (15 divided by 5) / 2 = 21 square centimeters, but why is 15 divided by 5 the height of a trapezoid
15. Let the area of a rectangle be a, and its perimeter s be expressed as a function of side length X Why not s = 4x
16. If the number of diagonal lines of a polygon is exactly 3 times of the number of sides of the polygon, then what is the sum of the inner angles of the polygon?
17. Find the number of polygon diagonal formula! Such as the title! To explain!
18. Given the quadratic function y = 2x square - 8x + 8 (1), write out the symmetry axis and vertex coordinates of the quadratic function (2) and judge whether (3,2) is in the direction of the quadratic function On the image
19. The quadratic function y = 7x & sup2; - (K-2) x + k-1 is known. When the value of K is, the function takes the y-axis as the axis of symmetry. Write out the analytic expression of the function.)
20. Find the relation of quadratic function satisfying the following conditions: the image passes through a (- 1,3) B (1,3) C (2,6) It's better to use a variety of methods. I'm in a hurry,