find the angles:-
In a triangle one of the sides is double of the other and the third angle is double of the first angle.
thanks!
The angles of a triangle always add up to $\displaystyle 180$ degrees. One side is double the other, so then $\displaystyle A=2B$, and the third angle is double of the first angle. This is slightly ambiguous as to what the first angle is, but I read it as being $\displaystyle A$, so $\displaystyle C=2A \Rightarrow 4B$.
Let's add up all the angles to equal one hundred and eighty degrees. $\displaystyle A+B+C=180$.
Write everything in the form of one variable. It so happens that B is the easiest.
$\displaystyle 2B+B+4B=180$
$\displaystyle 7B=180$
$\displaystyle B = \frac{180}{7}$
Solve for A and C.