A Aysun New member Joined Mar 29, 2019 Messages 2 Mar 31, 2019 #1 Hello!I don’t understand how to do this? If anyone could offer advice, I would appreciate it. Ex.1 In the triangle ABC are given BC = a, angle B = beta, angle C = gamma. Find the length of the inner bisector of the corner at the top A.
Hello!I don’t understand how to do this? If anyone could offer advice, I would appreciate it. Ex.1 In the triangle ABC are given BC = a, angle B = beta, angle C = gamma. Find the length of the inner bisector of the corner at the top A.
tkhunny Moderator Staff member Joined Apr 12, 2005 Messages 11,325 Mar 31, 2019 #2 Rather difficult to know how to help you without any idea what you know or should know or what you already have imagined. What are your thoughts? Did you draw a picture?
Rather difficult to know how to help you without any idea what you know or should know or what you already have imagined. What are your thoughts? Did you draw a picture?
A Aysun New member Joined Mar 29, 2019 Messages 2 Mar 31, 2019 #3 This is the image. And I think this should be the solution: \(\displaystyle \angle\)CAB=180 \(\displaystyle ^\circ\) - (\(\displaystyle \beta\) + \(\displaystyle \gamma\)) \(\displaystyle \Rightarrow\) \(\displaystyle \angle\)CAL=\(\displaystyle \angle\)LAB=\(\displaystyle \frac{180 ^\circ - (\beta+\gamma)}{2}\) here we use the sines law: \(\displaystyle \frac{AL}{sin\gamma}\)=\(\displaystyle \frac{CL}{\frac{sin180 ^\circ - (\beta+\gamma))}{2}}\) \(\displaystyle \Rightarrow\) \(\displaystyle \frac{AL}{sin\gamma}\)=\(\displaystyle \frac{2CL}{sin( \beta+\gamma)}\) \(\displaystyle \Rightarrow\) AL=\(\displaystyle \frac{2CL.sin \gamma}{sin(\beta+\gamma)}\) And if I use the sines law for the triangle ALB: AL=\(\displaystyle \frac{2LB.sin\beta}{sin(\beta+\gamma)} \) Is it right ? I'm sorry if I have made any mistakes.My English is not that good.
This is the image. And I think this should be the solution: \(\displaystyle \angle\)CAB=180 \(\displaystyle ^\circ\) - (\(\displaystyle \beta\) + \(\displaystyle \gamma\)) \(\displaystyle \Rightarrow\) \(\displaystyle \angle\)CAL=\(\displaystyle \angle\)LAB=\(\displaystyle \frac{180 ^\circ - (\beta+\gamma)}{2}\) here we use the sines law: \(\displaystyle \frac{AL}{sin\gamma}\)=\(\displaystyle \frac{CL}{\frac{sin180 ^\circ - (\beta+\gamma))}{2}}\) \(\displaystyle \Rightarrow\) \(\displaystyle \frac{AL}{sin\gamma}\)=\(\displaystyle \frac{2CL}{sin( \beta+\gamma)}\) \(\displaystyle \Rightarrow\) AL=\(\displaystyle \frac{2CL.sin \gamma}{sin(\beta+\gamma)}\) And if I use the sines law for the triangle ALB: AL=\(\displaystyle \frac{2LB.sin\beta}{sin(\beta+\gamma)} \) Is it right ? I'm sorry if I have made any mistakes.My English is not that good.
tkhunny Moderator Staff member Joined Apr 12, 2005 Messages 11,325 Mar 31, 2019 #4 What is it that you believe you do not understand? Did you make any errors on purpose?