MHT CET · Maths · Circle
The number of common tangents to the circles \(x^2+y^2-x=0\) and \(x^2+y^2+x=0\) is /are
- A 1
- B 2
- C 3
- D 4
Answer & Solution
Correct Answer
(C) 3
Step-by-step Solution
Detailed explanation
\(\begin{aligned} & x^2+y^2-x=0 \\ & \mathrm{C}_1=\left(\frac{1}{2}, 0\right), \mathrm{r}_1=\sqrt{\left(-\frac{1}{2}\right)^2+0^2-0}=\frac{1}{2} \\ & x^2+y^2+x=0 \\ & \mathrm{C}_2=\left(-\frac{1}{2}, 0\right), \mathrm{r}_2=\sqrt{\left(\frac{1}{2}\right)^2+0^2-0}=\frac{1}{2} \\ & \mathrm{C}_1 \mathrm{C}_2=\sqrt{\left(\frac{1}{2}+\frac{1}{2}\right)^2+0^2}=1 \\ & \mathrm{r}_1+\mathrm{r}_2=\frac{1}{2}+\frac{1}{2}=1 \\ & \mathrm{C}_1 \mathrm{C}_2=\mathrm{r}_1 \mathrm{r}_2 \\ & \Rightarrow \text { The given circles touch each other externally. } \\ & \Rightarrow \text { Number of common tangents }=3\end{aligned}\)
See the Complete Solution
Get step-by-step explanations for this and 2.5 Lakh+ more JEE, NEET & CET questions.
- Unlock all solutions
- Practice the full chapter
- Track accuracy across PYQs
4.8 rated on Google Play · 14,000+ reviews
More questions from Maths
- If \(\bar{a}\) and \(\bar{b}\) are vectors such that \(|\bar{a}+\bar{b}|=\sqrt{29}\) and \(\bar{a} \times(2 \hat{i}+3 \hat{j}+4 \hat{k})=(2 \hat{i}+3 \hat{j}+4 \hat{k}) \times \bar{b}\), then a possible value of \((\bar{a}+\bar{b}) \cdot(-7 \hat{i}+2 \hat{j}+3 \hat{k})\) isMHT CET 2022 Medium
- If \(P^{\prime}\left(A^{\prime}\right)+P\left(B^{\prime}\right) P(A \cup B)=0.7\) then \(P^{\prime}\left(A^{\prime}\right)+P\left(B^{\prime}\right)\) isMHT CET 2022 Medium
- If \(\frac{1-\tan \theta}{1+\tan \theta}=\frac{1}{\sqrt{3}}\), where \(\theta \in\left(0, \frac{\pi}{2}\right)\), then \(\theta=\)MHT CET 2020 Easy
- A die is thrown 100 times, then the standard deviation of getting an even number isMHT CET 2020 Medium
- The general solution of the equation \(3 \sec ^2 \theta=2 \operatorname{cosec} \theta\) isMHT CET 2023 Easy
- The area of the region bounded by the curves, \(y^{2}=8 x\) and \(y=x\) isMHT CET 2012 Easy
More PYQs from MHT CET
- Calculate \(\Delta \mathrm{H}^{\circ}\) for a reaction if \(\Delta \mathrm{S}^{\circ}=120 \mathrm{JK}^{-1}\) and \(\Delta \mathrm{G}^{\circ}=28000 \mathrm{~J}\)MHT CET 2025 Medium
- Equation of the plane, through the points \((-1,2,-2)\) and \((-1,3,2)\) and perpendicular to \(y z\) - plane, isMHT CET 2024 Easy
- Two bodies A and B have their moments of inertia \(I_1\) and \(I_2\) respectively about their axis of rotation. If their kinetic energies of rotation are equal and their angular momenta \(\mathrm{L}_1\) and \(\mathrm{L}_2\) respectively are in the ratio \(1: \sqrt{3}\), then \(\mathrm{I}_2\) will beMHT CET 2024 Medium
- Which hormone is produced by plants in adverse environmental conditions?MHT CET 2021 Hard
- Which one of the following acts as a pace setter of the human heart?MHT CET 2022 Easy
- How many pairs of sympathetic ganglia are present in ANS?MHT CET 2015 Hard