Medium.png
Answer variants:
\(\Delta CPD\)
\(PC\)
\(PD\)
\(CD\)
\(PB\)
diagonals
A rectangle \(ABCD\) has diagonals \(AC\) and \(BD\). A point \(P\) is chosen as a intersecting point of two daigoanls, such that \(\bigtriangleup APB\) is equilateral. Using this information, prove that \(∆CPD\) is also equilateral.
 
quad9.png
 
Proof: 
 
Given: \(ABCD\) is a rectangle  and diagonals intersect at \(P\).
 
\(\Rightarrow PA =\)
\(= AB\) - - - - - - (II)
 
We know that, "the
bisect each other".
 
\(PA =\)
and \(PB = \)
- - - - -- (III)
 
From (I), (II) and (III), we get that:
 
\(PA = PB =\)
\(=\)
\(= AB = CD\)

We obtained that in \(\Delta CPD\), \(PC = PD =\)
.
 
Therefore,
is an equilateral triangle.