[填空题]
The line $L_1$ has equation 2y−x−10=0 and is shown on the diagram.
The point A has coordinates (2,6)(2,6).
1.Show that A lies on $L_1$.
The point C has coordinates (8,18)(8,18). M is the midpoint of [AC].
2.Find the coordinates of M. (a,b) a= b=
3.Find the length of [AC]. AC ≈
The straight line, $L_2$, is perpendicular to [AC] and passes through M.
4.Show that the equation of $L_2$ is 2y+x−29=0.
The point D is the intersection of $L_1$ and $L_2$.
5.Find the coordinates of D.
The length of [MD] is $\frac{5\sqrt{5}}{4}$. (a,b) a= b=
6.Write down the length of [MD] correct to three significant figures.
The point B is such that ABCD is a rhombus. MD ≈
7.Find the area of ABCD. the area ≈
