Circles Quiz

1. What are the centre and radius of $(x+1)^2+(y-4)^2=9$?

• A. Centre $(-1,4)$, radius $3$
• B. Centre $(1,-4)$, radius $3$
• C. Centre $(-1,4)$, radius $9$
• D. Centre $(1,-4)$, radius $9$

2. Find the radius of the circle $x^2+y^2-10x+2y+1=0$.

• A. $5$
• B. $\sqrt{26}$
• C. $25$
• D. $\sqrt{27}$

3. The points $(1,3)$ and $(7,11)$ are the endpoints of a diameter. What is the centre?

• A. $(3,4)$
• B. $(6,8)$
• C. $(4,7)$
• D. $(3,7)$

4. The tangent to a circle at $T$ has gradient $-\frac25$. What is the gradient of the radius to $T$?

• A. $\frac25$
• B. $-\frac52$
• C. $-\frac25$
• D. $\frac52$

5. A circle has centre $(0,0)$ and radius $5$. What is the equation of the tangent at $(3,4)$?

• A. $3x+4y=25$
• B. $4x+3y=25$
• C. $3x-4y=25$
• D. $3x+4y=5$