An isosceles right triangle, whose hypotenuse is 8cm long, forms a 45 degree angle with the other side, and calculates its area If you want to use the method of elementary school mathematics, you can use it to calculate or solve the equation, but don't have any root sign and so on

Solution 1: let the length of one right side be a, because it is an isosceles right triangle, so the length of the other right side is also a
According to the Pythagorean theorem, the square of the hypotenuse is equal to the sum of the squares of two right angle sides
So (8 cm) &# 178; = A & # 178; + A & # 178;
2A & # 178; = 64cm & # 178;
A & # 178; = 32cm & # 178;
The area of this isosceles right triangle is equal to one right side x the other right side △ 2 = a × a △ 2 = A & # 178; △ 2 = 32cm & # 178; △ 2 = 16cm & # 178;
A: the area of this isosceles right triangle is 16 cm
Solution 2: use four identical isosceles right triangles to make a square. The side length of the square is the hypotenuse of the isosceles right triangle,
Therefore, the area of a square is 8 cm × 8 cm = 64 cm;,
So the area of each isosceles right triangle is 64 cm and 178; 4 = 16 cm and 178
A: the area of this isosceles right triangle is 16 cm

Is it so difficult? A spring scale is placed on the horizontal ground, q is the scale plate connected with the upper end of the light spring, P is a heavy weight, and the known mass of P is 10.5kg
It's so difficult? A spring scale is placed on the horizontal ground, q is the scale plate connected with the upper end of the light spring, P is a heavy weight, the known mass of P is m = 10.5kg, the mass of Q is m = 1.5kg, the mass of the spring is ignored, the stiffness coefficient is k = 800N, and the system is at rest

A spring scale is placed on the horizontal ground, q is the scale plate connected with the upper end of the light spring, P is a heavy weight, the known mass of P is m = 10.5kg, the mass of Q is m = 1.5kg, the mass of the spring is ignored, the stiffness coefficient is k = 800N, and the system is at rest

The fourth grade (Part Two)
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What about the question?

An elevator can transport 1.2 t goods from the ground floor to the top of the fourth floor in 10 s. if the height of each floor is 3.5 m, what is the power of the elevator? (g = 10 & nbsp; n / kg)

The elevator transports the goods with a mass of 1.2 t from the ground floor to the top of the fourth floor at a uniform speed. The work done by the elevator is w = GH = 1.2 × 103 × 10 × 3.5 × 4 = 1.68 × 105J. According to the power formula P = wt = 1.68 × 10510 = 1.68 × 104w; a: the work done by the elevator is 1.68 × 104w

If the number of terms of the arithmetic sequence an is odd, A1 = 1, the sum of odd terms of an is 175, and the sum of even terms of an is 150, the tolerance D of the arithmetic sequence can be obtained

Because the number of terms is 2N-1
S odd + s even = 325
S odd-s even = an (an is the middle term)
S odd / s even = 7 / 6
(there is a formula s odd / s even = n / n-1) s odd = n * an, s even = (n-1) * an
So n = 13
Sn=325
Sn=na1+{n(n-1)/2}d
Calculate the tolerance D
So d = 4
Remember to evaluate in time, I hope our work can be recognized, which is also the driving force for us to move forward!

(1) if the vehicle accelerates at an acceleration of 0.6m/s2, what is the speed after 10s? (2) If the vehicle brake decelerates at an acceleration of 0.6m/s2, what is the speed reduction after 10s? (3) If the car brake decelerates with an acceleration of 3m / S2, what is the speed after 10s?

(1) the speed at the end of 10s is v = V0 + at = 11 + 0.6 × 10m / S = 17m / S; (2) the speed at the end of 10s is v = V0 + at = 11-0.6 × 10m / S = 5m / s when the time to zero is t0 = 0 − v0a = 110.6s ≈ 18.5s. (3) the time to zero is t0 = 0 − v0a = − 11 − 3S ≈ 3.7s

Xiaogang and Xiaoyong run a 50 meter race. As a result, when Xiaogang reaches the finish line, Xiaoyong is still 10 meters behind Xiaogang. In the second race, Xiaogang's starting line is 10 meters back, and they still run at the first speed. The result of the race will be ()
A. When Xiaogang reaches the end, Xiaoyong falls behind 2.5 meters B. when Xiaogang reaches the end, Xiaoyong falls behind 2 meters C. when Xiaoyong reaches the end, Xiaogang falls behind 2 meters D. Xiaogang and Xiaoyong reach the end at the same time

(50 + 10) × (40 △ 50) = 60 × 45, = 48 (m). 50-48 = 2 (m). That is to say, Xiaoyong is 2 meters behind when Xiaogang reaches the terminal

If x is a positive number and Y is a negative number in the solution of equation system (1) kx-y = 7 (2) 3x + 2ky = 5, the value range of K is obtained
The answer is - 5 / 14

Let's take K as a constant first. Through simultaneous (1) kx-y = 7 equations, we can use K to express x, y
（2）3X+2KY=5
x=(42k+15)/(6k^2+9),
y=(5k-21)/(2k^2+3)
According to the theme, (42K + 15) / (6K ^ 2 + 9) > 0, (5k-21) / (2k ^ 2 + 3)

It is known that on the number axis, points a and B represent rational numbers a and B respectively, and the origin is just the midpoint of ab. find the value of 1 / 2009ax2010
My formula is 1
（2009 X -b）X ——
2010b
one
= -2009b X ——
2010b
two thousand and nine
= - ——
two thousand and ten

It is known that on the number axis, points a and B represent rational numbers a and B respectively, and the origin is just the midpoint of AB, a = - B;
-(2009) / (2010); your calculation is correct!

25% = 90 divided by () = fractions = () the last bracket is filled with decimal, the ratio of the second, a and B is 4:5, the number a is (), the number B is (), the number a is () less than the number B, and the number B is () more than the number A. if the number a is 40, the number B should be () if the sum of the two numbers a and B is 45, the number a is (), the number B is (). The number 3 and a are 20, The number B is 60% of the number a, and 4 / 5 of the number C is the number B. the number C is (). 4. The farm used 1500 duck eggs to float chickens, and 5% of them did not float out, and () chickens floated out. The fruit of the 5th and 10kg increased by 10%, and then decreased by 10%, and the result was () kg. 6. 50% of the number a is equal to 40% of the number B, and the reciprocal of the number a is 5 / 2, then the number B is ()

1. 25% = 90 divided by (22.5) = 1 / 4 = (0.25)
2. The ratio of a and B is 4:5, the number of a is (80)%, the number of B is (125)%, the number of a is (20)%, the number of B is (25)%, if the number of a is 40, the number of B should be (50); if the sum of a and B is 45, the number of a is (20), the number of B is (25)
3. The number a is 20, the number B is 60% of the number a, and four fifths of the number C is the number B. the number C is (15)
4. The farm used 1500 duck eggs to float chicks, 5% of them didn't float out, and (1425) were floating out
5. 10 kg fruit increased by 10%, then decreased by 10%, the result is (9.9) kg
6. If 50% of the number a is equal to 40% of the number B, and the reciprocal of the number a is 5 / 2, then the number B is (#)

An isosceles right triangle, whose hypotenuse is 8cm long, forms a 45 degree angle with the other side, and calculates its area If you want to use the method of elementary school mathematics, you can use it to calculate or solve the equation, but don't have any root sign and so on