$\sin\left({2x}\right)=\frac{ 7 }{ 20 }$
$2x=\arcsin\left({\frac{ 7 }{ 20 }}\right)$
$\begin{array} { l }2x=\arcsin\left({\frac{ 7 }{ 20 }}\right),\\2x={180}\degree-\arcsin\left({\frac{ 7 }{ 20 }}\right)\end{array}$
$\begin{array} { l }\begin{array} { l }2x=\arcsin\left({\frac{ 7 }{ 20 }}\right)+{360}\degreek,& k \in ℤ\end{array},\\2x={180}\degree-\arcsin\left({\frac{ 7 }{ 20 }}\right)\end{array}$
$\begin{array} { l }\begin{array} { l }2x=\arcsin\left({\frac{ 7 }{ 20 }}\right)+{360}\degreek,& k \in ℤ\end{array},\\\begin{array} { l }2x={180}\degree-\arcsin\left({\frac{ 7 }{ 20 }}\right)+{360}\degreek,& k \in ℤ\end{array}\end{array}$
$\begin{array} { l }\begin{array} { l }x=\frac{ \arcsin\left({\frac{ 7 }{ 20 }}\right) }{ 2 }+{180}\degreek,& k \in ℤ\end{array},\\\begin{array} { l }2x={180}\degree-\arcsin\left({\frac{ 7 }{ 20 }}\right)+{360}\degreek,& k \in ℤ\end{array}\end{array}$
$\begin{array} { l }\begin{array} { l }x=\frac{ \arcsin\left({\frac{ 7 }{ 20 }}\right) }{ 2 }+{180}\degreek,& k \in ℤ\end{array},\\\begin{array} { l }x={90}\degree-\frac{ \arcsin\left({\frac{ 7 }{ 20 }}\right) }{ 2 }+{180}\degreek,& k \in ℤ\end{array}\end{array}$
$\begin{array} { l }\begin{array} { l }x\approx{10.2}\degree+{180}\degreek,& k \in ℤ\end{array},\\\begin{array} { l }x\approx{79.8}\degree+{180}\degreek,& k \in ℤ\end{array}\end{array}$
4.4