Use Coupon: CART10 and get 10% off on all online Study Material

Total Price: R

There are no items in this cart.
Continue Shopping
Get instant 50% OFF on Online Material.
Use coupon code: MOB50 | View Course list

two tangents are drawn from the point (-2,-1) to a parabola. if thita is the angle between them, what is the value of tan thita

3 years ago


Answers : (2)


Hi Rupali,


You've not mentioned the equation of the parabola. (Assuming it as y^2 = 4x)


The eqn of any tangent to a parabola y^2 = 4ax is y = mx+a/m


So the equation of any tangent to this parabola, would be y=mx+1/m (as a=1, for y^2=4x)

Now these tangents pass through (-2,-1)... so -1=-2m+1/m

Or 2m2-m-1=0.

Where m1,m2 are the slopes of the two tangents that satisfy this equation (m1,m2 are the roots of the quad)....


So tan(angle between the tangents) = |(m1-m2)/(1+m1m2)|

Now m1m2 = -1/2

And m1-m2 = root { (m1+m2)2-4m1m2 } = root [ (1/2)2 - 4(-1/2) ] = root[9/4].

So |m1-m2| = 3/2.


Hence tan(Angle) = (3/2) / (1/2) = 3.....


And that is the answer.


Best Regards,

Ashwin (IIT Madras).

3 years ago

You have to give the equation of parabola.

3 years ago

Post Your Answer

What is the best book for concepts in physics?
you can get the solutions of HC Verma book on this youtube channel named “Omega Open Course”
Sundar Chacha one month ago
hc verma best physics concept book really ive tried it just blindly follow it
purva gupta 2 months ago
Which book should i take to begin physics for iitjee ?i am in class 10.
Dear Student, Write now you can mainly focus on your ncert books only. Thanks.
Vijay Mukati 3 months ago
My guidelines for you are –Stay focused on your studies and keep in mind that one must focus on Physics, Chem and Maths, try to fortify these three, take some coaching classes from a...
Ayushmaan Vardhan 3 months ago
U can start hc Verma for physics if u hav some one around to clarify ur doubts or else u may confuse ur self …....wish u good luck ...if u see an ans also do reply like ..thanks or tell...
Riddhi Gupta 21 days ago
Sir i got AIR 85680 in obc category in jee mains,can i get admission in NIT in electrical engineering
Getting core branches is difficult for you. You may be requred to wait upto spot round for getting this.
Vijay Mukati 2 months ago
Its difficult to say at this moment.
Vijay Mukati 2 months ago
Tier 2 or tier 3 NITs.
Vijay Mukati 2 months ago
I am preparing for jee on my own and i wanted to clear one thing should we learn only the topic that are given on the site sylabus jee advance? Eg only keto-enol tautomerism is given but...
Dear Student, First thing is that you should go through the syllabus completely. The given syllabus is in breief and hence the subtopics are not mentioned there. Therefore I will suggest you...
Vijay Mukati 2 months ago
Thanks a lot sir.... So i should do everything.. The portion is just the main ones.. Thank u
Topper 2 months ago
Respected Sir, If one gets a rank between 900 to 1000 in JEE Advance, which IIT & which branch he may get.
Dear Student, 900 to 1000 is good AIR and you can definately get the core branches in few older IITs. Best of Luck for your preparation. Thanks.
Vijay Mukati one month ago
i am scoring 400 and i am an obc in aipmt re test.can i get mbbs or bds .my home is west bengal
Chances are very less because the paper this year was easy and the cut off will be high. Did you get anything through WBJEE?
Neeti 2 months ago
View all Questions »
More Questions On IIT JEE Entrance Exam

Ask Experts

Have any Question? Ask Experts

Post Question

Answer ‘n’ Earn
Attractive Gift
To Win!!!
Click Here for details