+ 3! + - 5! + - 4! + - 1! + - 2

+ 3! + - 5! + - 4! + - 1! + - 2

#include "iostream"
using namespace std;
int fun(int n)
{
    int sum=1;
    int i;
    for(i=1;i<=n;i++)
           sum*=i;
     return sum;
}
 
int main()
{
       int i,mark=1;
       int sum=0,item=0;
       for(i=1;i<=9;i++)
       {
            item=mark*fun(i);
            sum+=item;
            mark=-mark;
       }
       cout<<"1!-2!+3!-4!+5!-6!+7!-8!+9!="<  
}

If cos (PAI / 6-alpha) + sin alpha = four fifths root three, then sin (alpha + seven sixths) is the value What is the value

 cos (PI / 6-alpha) + sin  Alfa = four times the five times root three  cos (π / 6) cos α + sin (π / 6) sin α + sin α + sin α = 4 √ 3 / 5  3 / 2) cos α + (3 / 2) sin α = 4 √ 3 / 5  3  3  3 ȿ 3 \\\\\\\\\\\\\\\\\\α * si

As shown in the figure, the image of the line y = 2x + 2 intersects with the X axis at point a The intersection line y = 2x + 2 of the straight line passing through point B (3,0) is at point P, and the area of △ PAB is 6

A(-1,0) B(3,0)
So the ordinate of point P is 3 or - 3
So the point P coordinates are (1 / 2,3) or (- 5 / 2, - 3)
So the analytic formula is y = 6x or y = 6 / 5x

If the largest angle of a triangle is an acute angle, then the triangle must be a () triangle

Acute triangle

A triangle with two acute angles must be judged as an acute triangle Two lines perpendicular to the same line must be parallel

1. No, all triangles have two acute angles
2. Yes

On the problem of trigonometric function, COSC = 2 √ 2 / 3, a is an acute angle and f (A / 2) = - 1 / 4 A + C = 2 + 3 √ 3 to find the area of triangle ABC

From COSC = - 2 √ 2 / 3,
Sinc = 1 / 3;
And - √ 3 / 2sina + 1 / 2 = - 1 / 4,
Sina = √ 3 / 2;
From the sine theorem,
A = 3 √ 3 / 2C was obtained;
Put in the last formula;
C = 2, a = 3 √ 3;
Finally, s = 1 / 2acsinb; comes out

Draw the largest square in a circle. The side length of the square is 1 meter. Find the area of the circle By the way, add 25 points

Draw a largest square in a circle. Take this square as four small triangles. The base and height of each small triangle are radius. Therefore, the area of a small triangle is the square of radius and divided by 2. The area of four small triangles is equal to the square of radius divided by 2 and multiplied by 4, which is equal to twice the square of radius,
Square area: 1 * 1 = 1 square meter,
So the radius of the square is one half of a square meter,
Area of circle = 3.14 * square of radius,
=3.14 * 0.5 = 1.57 square meters

There are two squares. The side length of the big square is 4 decimeters longer than that of the small square, and the area of the big square is 80 square meters Only two days! It's due on Sunday!

80-4 × 4 = 64 square centimeter
64 △ 4 △ 2 = 8 cm. This is the side length of a small square
Area: 8 × 8 = 64 square centimeter

What is the formula for calculating the area of a hexagon? I faint! I have area now, want to grow longer! How to do?

Area formula of regular n-polygon
S=C*r/2
C -- perimeter
R -- radius
The regular hexagon C = 6, r = 1, so s = 6 * 1 / 2 = 3

If AB = 3, BC = 4, CD = 5, ad = 6, then cosa is known=______ .

Connect BD,
According to the cosine theorem, BD2 = 9 + 36-2 × 3 × 6cosa = 45-36cosa,
BD2 = 16 + 25-2 × 4 × 5cosc = 41-40cosc,
∵A+C=180°，∴cosC=-cosA，
ν 45-36cosa = 41 + 40cosa, cosa = 1
19．
So the answer is: 1
19．