Use Coupon: CART20 and get 20% off on all online Study Material

Total Price: R

There are no items in this cart.
Continue Shopping
Get instant 20% OFF on Online Material.
coupon code: MOB20 | View Course list

Get extra R 120 off


If the incircle  of the  triangle ABC passes through its circumcentre, then prove that cosA

+cosB+cosC = √2


5 years ago


Answers : (1)


Dear student,

The circle passing through the vertices of the triangle ABC is called the circum-circle. Its radius R is called the circum-radius. In the triangle

ABC, R = a/2 sin A = b/2 sin B = c/ 2 sin C = abc/4Δ.


From here we can deduce that 

cosA+cosB+cosC = √2


Please feel free to ask your queries here. We are all IITians and here to help you in your IIT JEE preparation.

All the best.

Win exciting gifts by answering the questions on Discussion Forum. So help discuss any query on askiitians forum and become an Elite Expert League askiitian.

Now you score 5+15 POINTS by uploading your Pic and Downloading the Askiitians Toolbar  respectively : Click here to download the toolbar..


Askiitians Expert

Sagar Singh

B.Tech, IIT Delhi

5 years ago

Post Your Answer

Other Related Questions on Trigonometry

Prove That: sinA-sin3A+sin5A-sin7A ------------------------------------- =cot2A cosA-cos3A-cos5A+cos7A
Apply sinc – sind formulaes in numerator and cosc – cosd in denmoinator with first (2-2)pair and U would sort out in the finally to cot2a.
Vikas TU 2 months ago
If sinA+sinB+sinC+sinD=4 then find sinA.sinB.sinC.sinD.
If sinA+sinB+sinC+sinD=4 is given, then it would only be 4 when all sins would attain its maximum value from its range that is 1. therfore sinA = sinB =sinC =sinD = 1. And thus the product...
Vikas TU 3 months ago
if sin a +sin b +sin c +sin d =4 then sina.sinb.sinc.sind =1 getting maximam vatue lesser equals 1 sin A =SIN B =SIN C=SIN D=1 SO sin A.SIN B.SIN C.SIN D =
SYED FAHIM AHAMAD 2 months ago
Please clear my confusion about find value of tan7.5 °.
Yaa... tan15°=2tan7.5°∕1-tan²7.5° ⇒2-√3=2tan7.5°/1-tan²7.5° . By solving this eq i got value of tan7.5°= (√2-1)(2+√3) . But Ans is (√3-√2)(√2-1). How?
ANKIT ANAND one month ago
What`s your confusion with tan7.5° .Kindly elaborate that where you have stuck?.If you will elaborate then I can help you better.
Sagar Gupta one month ago
@ ankit u have to apply the following formula sin ( a/2 ) = [(1-cosa)/2] ^ ½ cos a/2 = [(1+cosa)/2] ^ ½ tan 2a = [2 tan a ] / [1+tan square (a) ] answer is = root6-root3 +(root 2 ) -2 HOPE...
Umakant biswal one month ago
how to obtain your math notes.
You can purchace online from its website. Thanks.
Vijay Mukati one year ago
certain notes are available free. you can also vist some other sites, where free notes of each subject is available. please surf the web to find such sites. it is better to get free notes...
vindhya one year ago
If A1,A2,A3, in AP such that, A1+A5+A10+A15+A20+A24=225, then, A1+A2+A3+...A23+A24 is equal to?
A1,A2,A3, in AP the write in common terms of a and d. .i.e. A1 = a A2 =a+d A3 =a+2d . . A24 = a+23d summing all we get, 4(6a+69d) = > 4*225 = 900 perhaps.
Vikas TU 3 months ago
u can also solve in such way, (A1+A24) +(A5+A20) +(A10+A15)=225. THEREFORE 3(A1+A24)=225 (A1+A24)=75. NOW SUM=24/12(A1+A24) =900
krunal 2 months ago
View all Questions »

  • Complete JEE Main/Advanced Course and Test Series
  • OFFERED PRICE: R 15,000
  • View Details
Get extra R 3,000 off

Get extra R 120 off

More Questions On Trigonometry

Ask Experts

Have any Question? Ask Experts

Post Question

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