Conics: deriving tangent/normal (1 Viewer)

[Mr-Morten]

Hey, In the conics topic, if part of a question requires use of e.g. a tangent or a normal, are we required to derive the formula from scratch or can we just quote the standard form (e.g. x.x1/a^2 + y.y1/b^2 = 1 for the tangent to an ellipse) and go from there? I have been under the impression that, even if it doesn't explicitly state it, we are required to derive the formula; but i want to be sure as it could save some time in the exam if i'm mistaken.

 

[Dumbledore]

unless it says "you may assume ...etc" then u have to derive it for tangents and normals

for chord of contact, u can state it unless it asks u to prove it

 

[Mr-Morten]

Thanks, that's what i was thinking

 

[kwabon]

derive derive derive unless it says assume, dumbledore is quite right, but unfortunately HE IS DEAD!!! :-(

 

[annabackwards]

derive derive derive unless it says assume, dumbledore is quite right, but unfortunately HE IS DEAD!!! :-(

HP fan right here XD