IIT JEE , AIEEE Forum - Mathematics , Trignometry

magiclko

Hiiiiii folks,

here's one question in which m badly stuck....

in a triangle ABC, the medians BE and CD intersect at right angles, then find the minimum value of cotB + cot C.....

the answer is,(as u all we would hav guessed,) 2/sqrrt3....but i wanna knw the complete method of this question!!!

avdesh100

check out the physics solution.

tejasvi2389

manasi where are u studying

magiclko

nowhere, m studying on my own....y u asked???

be_cool978

magiclko

no reply

shakirshafi12

hey manasi i just tried out ur problem and i was usin the prop
in which angle in a semi circle is 90 degree we get 3 cricles

magiclko

how this will help in solving the question!!!

shakirshafi12

(cotA+cotB+cotC)/3>=cot((A+B+C)/3)
cotB+cotC=sqroot(3)-cotA
this equality will hold only if A=B=C
then cotA+cot B=2/sqroot(3)
in equilateral triangle anglebisectors and medians r same and intersect at 90
but the problem is i havent used the prop that they intersect at right angles!!!!
that was why i was suggesting draw semicircles and use some gd prop there

magiclko

btw shakir have u solved the physics subjective question in open test whr, thr were 5 plates nd some charge were given on it nd then potential difference was asked..... wat hav u got the answer??? m getting it 2 and the answer given in solution is 1....wat was urs???

magiclko

shakir, medians of an equilateral triangle dnt intersect at rite angles, do they

...... nd if directly we take A=B=C, we can put the value of cot 60 directly....isnt it???

shakirshafi12

i did nt do that in paper but yes i tried at home and im vry confused that it is comin 2 as u r sayin .

ya really a silly mistake i have commited actually bcoz i is a big doubt of urs i think i will have to solve the problem on paper. an draw diagram

magiclko

it is cuming 2.....i did it in the paer too and at home also.... nd even some of my frnds are also getting 2...but the answer given is 1....newayz thanx

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