Answer:
The radius of the given equation is 2 .
Step-by-step explanation:
The equation of a circle whose center (h, k) and radius is r,
(x - h)² + (y - k)² = r² ..............................(i)
Here given that-
x² + y² + 21 = 10 x
<em>x² - 10 x + y² + 21 = 0</em>
<em>( To making perfect square, add and subtract 25 ) -</em>
<em>x² - 10 x + 25 - 25 + y² + 21 = 0 </em>
<em>(x² - 10 x + 25) + y² -4 =0</em>
[As we know that -
(x - 5)² = x² - 10 x + 25]
<em>(x - 5 )² + y² = 4</em>
<em>(x - 5)² + (y - 0)² = 4</em>
<em>(x - 5 )² + (y- 0)² = 2² ................................(ii)</em>
On comparing equation (i) and(ii)-
r = 2
Hence the radius of the given equation is 2 and center is ( 5, 0).
Answer:
its 45
reason is 216-81 = 135 divide by 135/3=45
I hope this helps you
Surface Area= 2.pi.r.h+2.pi.r^2
Surface Area =2.pi.3/2.10+2.pi. (3/2)^2
Surface Area =30pi+4,5.pi
Surface Area =34,5.pi
I'm Pretty Sure The Answer Is 31