Vì tam giác ABC cân tại A (gt) mà AM là đg trung tuyến nên AM đồng thời là đg cao của t/giác đó:
AM là trung tuyến của t/giác ABC nên M là trung điểm BC:
=> BM =BC/2 =6:2=3(cm)
Xét tam giác AMB vuông tại M
AB^2 =AM^2+BM^2 ( theo định lý Py-ta -go)
Answer:
Step-by-step explanation:
B
Answer:
Given :A star in the sky appears to move by 12 arc seconds over the course of 6 months.
To Find :Convert this number into first arc minutes then degrees.
Solution:
60 arc seconds = 1 arc minute
1 arc seconds = 
arc minute
12 arc seconds = 
arc minute
12 arc seconds = 
arc minute
So, 12 arc seconds = arc minute
Now convert it into degrees
60 arc minute = 1 degree
1 arc minute = degree
arc minute = 
degree
arc minute = 
degrees
12 arc seconds = degrees
Step-by-step explanation:
The equation of a circle can be the expanded form of
\large \text{$(x-a)^2+(y-b)^2=r^2$}(x−a)
2
+(y−b)
2
=r
2
where rr is the radius of the circle, (a,\ b)(a, b) is the center of the circle, and (x,\ y)(x, y) is a point on the circle.
Here, the equation of the circle is,
\begin{gathered}\begin{aligned}&x^2+y^2+10x-4y-20&=&\ \ 0\\ \\ \Longrightarrow\ \ &x^2+y^2+10x-4y+25+4-49&=&\ \ 0\\ \\ \Longrightarrow\ \ &x^2+y^2+10x-4y+25+4&=&\ \ 49\\ \\ \Longrightarrow\ \ &x^2+10x+25+y^2-4y+4&=&\ \ 49\\ \\ \Longrightarrow\ \ &(x+5)^2+(y-2)^2&=&\ \ 7^2\end{aligned}\end{gathered}
⟹
⟹
⟹
⟹
x
2
+y
2
+10x−4y−20
x
2
+y
2
+10x−4y+25+4−49
x
2
+y
2
+10x−4y+25+4
x
2
+10x+25+y
2
−4y+4
(x+5)
2
+(y−2)
2
=
=
=
=
=
0
0
49
49
7
2
From this, we get two things:
\begin{gathered}\begin{aligned}1.&\ \ \textsf{Center of the circle is $(-5,\ 2)$.}\\ \\ 2.&\ \ \textsf{Radius of the circle is $\bold{7}$ units. }\end{aligned}\end{gathered}
1.
2.
Center of the circle is (−5, 2).
Radius of the circle is 7 units.
Hence the radius is 7 units.
