1, wrong 2, wrong 3, wrong 4, wrong 5, wrong 6, wrong 7, wrong 8, wrong 9, wrong 10, wrong1,wrong 12, wrong 65438 in the case of three dimensions.

4. Application questions

1、

① from the general formula of arithmetic progression, the solution is a4 = 2+(4-1) * 3 = 2+9 =11.

②a 1 = a5-(5- 1)*(-3)= 8+ 12 = 20

2. Solution:

① it is known that a4= 1 1, a6= 17, and the general formula of arithmetic progression is d = (a6-a4)/2 = (17-1)/2 = 3.

a 1 = a4-3d = 1 1-9 = 2

S6 = 0.5 * 6 *(a 1+a6)= 3 *(2+ 17)= 3 * 19 = 57

3、

Solution: According to the topic, we know that point (0,0) and point (1, 3) fall on the straight line y=3x, so we can know that the sine of angle A is 3 √ 10/ 10.

Cosine =√ 10/ 10, tangent =3.

4、

Solution: Sine =-4/5, Cosine =-3/5, Tangent = 4/3 of Angle A.

5、

Solution: Use the distance formula from point to straight line: d=(4-3+4)/√5=√5.

6、

Solution: The slope k of the straight line L = (2-(-5))/(1-(-1)) = 7/2.

The straight line is parallel to the straight line L. If it passes (2,3), then y-3=(7/2)(x-2), and the order is 2y=7x-8.

7、

Solution: The slope of the straight line perpendicular to the straight line x-y-2=0 is-1.

If the line to be found passes through (4, 1), then y- 1=-(x-4) sort: y=-x+5.

8、

Solution: The distance from the center of the circle to the Y axis is 3. Then the standard equation for finding a circle in the problem is: (x+3) 2+(y-6) 2 = 9.