What is the angle needed to solve this right triangle?

Join the discussion
Registration is free. Ask a follow-up in this thread, or start your own.
4 replies · 2K views
nmnna
Messages
22
Reaction score
3
Homework Statement
In figure ##\angle{ABC} = 90^\circ = \angle{BCD}, \ \angle{ACB} = 41.45^\circ, \ \angle{CBD} = 32.73^\circ, \ BC = 10##cm. Calculate ##AB, \ CD## and ##\angle{AEB}##
Relevant Equations
##\tan{\alpha} = \frac{opposite \ side}{adjacent \ side}##
The Figure
1616228240588.png

My Attempt at Solution

##\tan{ACB} = \frac{AB}{BC}, \ \tan41.45^\circ = \frac{AB}{10} \Rightarrow AB = 10\tan45.41^\circ \approx 8.83##cm
Similarly
##\tan{CBD} = \frac{CD}{BC}, \ \tan32.73^\circ = \frac{CD}{10} \Rightarrow CD = 10\tan32.73^\circ \approx 6.43##cm
After this I checked the answer in my textbook, and instead of 6.43cm the answer for ##CD## was 4.40cm.
I thought that there was a typo in the problem, so instead of ##32.73^\circ##, I tried ##23.73^\circ##, and surprisingly the answer matches with the one in the textbook.
So I'd like to know if it really is a typo or my solution is wrong.
And I can't find the angle required in the problem, so I'd be grateful if you give me some hints for finding this angle.
 
Reply
  • Like
Likes   Reactions: PeroK
Physics news on Phys.org
PeroK said:
You have angle ##BCD## twice there. Please clarify.
It should be ##ACB##
 
nmnna said:
So I'd like to know if it really is a typo or my solution is wrong.
And I can't find the angle required in the problem, so I'd be grateful if you give me some hints for finding this angle.
Looks like a typo.

A hint to find the angle ##AEB##. First extend the line ##AB## to a new point, ##F##, so that ##AFD## is a right angle. Then you have another angle equal to ##AEB##.
 
Reply
  • Like
Likes   Reactions: FactChecker, Lnewqban and nmnna