高校数学の質問スレ（医者・東大卒専用） Part438

>>762
r=4/√(15)
https://i.imgur.com/jaKy6PU.png


Wolfram Language 14.0.0 Engine for Microsoft Windows (64-bit)
Copyright 1988-2023 Wolfram Research, Inc.
In[1]:= Sqrt[2^2-(1/2)^2]
Sqrt[15]
Out[1]= --------
2
In[2]:= Solve[Sqrt[15]/2 - (1/2)Sqrt[-1+4r^2] == r,r]
4
Out[2]= {{r -> --------}}
Sqrt[15]