Hello student ,

Since both forces have equal magnitude F1 = F2 = F

Since its given that the resultant force is equal to magnitude of one of the two forces F(resultant)= F

Therefore

F(R) = sqrt of F1^2 + F2^2 + 2F1F2Cos(theeta)

Substituting values of F

F = sqrt of F^2 + F^2 + 2F^2Cos(theeta)

Squaring on both sides we get

F^2 = 2F^2[1+Cos(theeta)]

Canceling F^2 on both sides we get

1/2 -1 = Cos(theeta)

Therefore ,

Theeta = cos inverse of  -1/2

= 2Pi/3

Hi Dipak, hope you are doing well,

Let the forces be F1 and F2
F1^2 + F2^2 = 90 N
(as the angle between them is 90° or right angle)
when angle is 60°
F1^2 + F2^2 + 2 * F1 * F2 *cos(60)=117 N
90 + F1 * F2=117

F1 * F2 = 27
(F1 + F2)^2 = F1^2 + F2^2 + 2 * F1 * F2 = 90+27×2=144
F1 + F2 = 12..............(i)
F1 - F2 = √( ( F1 + F2)^2 - 4F1 * F2) = √36 = 6.........(ii)
from eq.(i) and (ii) We get....
F1 = 9 N ,and F2 = 3 N

Feel free to ask doubts in the Comment Section like this.

I hope this helps you.

Thanking you

Yours sincerely

Somenath Chattopadhyay

HI Kishor,

If you are preparing for GATE than the best books for Engineering Mechanics are as follows:-

• Engineering Mechanics- New Age International by S S Bhavikatti
• Higher engineering Mathematics by B S Grewal

You may buy any one or both to boost up your prepaartion.

Refer here for more info - https://engineering.careers360.com/articles/what-are-best-books-for-gate-me

Feel free to ask doubts in the Comment Section.

I hope this information helps you.

Good Luck!

hi mohammed,

Firstly, don't be afraid of the exam. Ask some senior who are great in academics for advice. Don't as from seniors who themselves got barely passed in this subject.

Analyze previous year papers of engineering mechanics, see what is important and if something is similar in all the exams. You need practice in engineering mechanics, that means you can't leave this subject just for a day before exam. You will surely fail. You may be not good with mechanics from your 12th. Its okay you can learn now, go to the teacher's staff room if you have some problem. Go even if your friends is not going with you to the teacher for doubt clearing. You have given internals only as of now. External exam have a good amount of weightage, if you study hard you can pass easily after getting good marks in external. As of now, in quarantine try to read from books, youtube etc.

I hope this answer will help.
All the best for the future!!

Hello dear aspirant.

I know civil engineering is one of the toughest branch in engineering specially because of these subjects like mechanics , engineering drawing , strength of materials etc. If you are not understanding them properly then have patience and practice as much as you can take the help of you tube and reference books. These are the only best options.

Hope it helps.

Good luck

Hello Aspirant,

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