Sin43 ° cos43 ° should be accurate to 0.0001

Sin43 ° cos43 ° should be accurate to 0.0001

sin43cos43=-0.4617292235

5 / 8 of a number is 15, and 2 / 3 of the number is 15

The number is: 15 (5 / 8) = 15 × 8 / 5 = 24
Two thirds of this number is: 24 × 2 / 3 = 16

Set up equations and find out the solution of the equation: the sum of 6.5 times of a number plus 4.2 is 38.9, what is the number? (set up equations)

Let this number be X
6.5X+4*4.2=38.9
6.5X+16.8=38.9
6.5X=38.9-16.8
6.5X=22.1
X=22.1÷6.5
X=3.4

How many parts of one meter is five ninths of a meter? How many parts of five meters?

5 / 9 △ 1 = 5 / 9
5 / 9 △ 5 = 1 / 9
A: five ninths of a meter is five ninths of a meter and one ninth of a five meter

Solve this equation: 3:5 = 90: X

The solution is 3:5 = 90: X
90 × 5 = 3x
That is, 3x = 450
That is, x = 150

Sin25°Cos20°+ Cos20°Sin20°=

The original formula is sin (25 ° + 20 °) = sin 45 ° = 2 / 2 root sign 2

Sorry, it's wrong. 56 × [1 - 5 / 8] = [56 + x] × 3 / 10

56 × [1-5 / 8] = [56 + x] × 3 / 10
56-35=3(56+x)/10
210=3(56+x)
x+56=70
x=14

How many steps is Tan (- 31 / 4 π) equal to

The original formula = Tan (- 8 π + π / 4)
=tan(π/4)
=1

The endpoint of line segment PQ with length 6 slides on ray y = 0 (x ≤ 0) and x = 0 (Y ≤ 0), and point m is on line segment PQ with MQ = 2pm
1. Find the trajectory equation of point M
2. If the locus of point m intersects with x-axis and y-axis at points a and B respectively, find the maximum area of oamb

First question: let P (x, O) Q (0, y) m (a, b)
From the question: x ^ 2 + y ^ 2 = 36
a=2/3*x
b=1/3*y
Taking X and Y into the equation, we get the trajectory equation a ^ 2 / 4 + B ^ 2 = 4 of M

Prove the periodicity of function
1. The image of F (x) is symmetric with respect to the line x = B and x = A. (b > A)
It is proved that f (x) is a periodic function and T = 2 (B-A)
2. F (x) satisfies that f (x) = f (x-a) + F (x + a) (a belongs to R +)
It is proved that f (x) is a periodic function and T = 6A

1. Because the image of F (x) is symmetric with respect to the line x = B and x = a
So f (x) = f (2a-x) f (x) = f (2b-x)
f(2a-x)=f(2b-x)
Let 2a-x = t, then x = 2a-t
The original formula becomes f (T) = f (2b-2a + T) = f (T + (2b-2a))
Because of the arbitrariness of T, f (x) is a periodic function and T = 2b-2a
2. Because f (x) = f (x-a) + F (x + a)
So f (x + a) = f (x) - f (x-a)
Then f (x + 6a) = f (x + 5A + a) = f (x + 5a) - f (x + 4a) = f (x + 4a) - f (x + 3a) - f (x + 3a) + F (x + 2a) =... = f (x)
F (x) is a periodic function and T = 6A