Question

ABCD is a rhombus such that $\angle ACB={50}^o,$ find $\angle ADB$.

• A. ${50}^o$
• B. ${40}^o$
• C. ${60}^o$
• D. ${30}^o$

Answer 1

The correct option is B ${40}^o$

$\angle ACB={50}^o,\angle ACB=\angle CAD(\because BC||AD)$
In $△AOD,\angle DAO+\angle ADO+\angle AOD={180}^o$
$50+\angle ADB+{90}^o={180}^o$
$\angle ADB={180}^o-{140}^o=40$