Question

solve the first sum fast​

Answer 1

First of all, join

EOD

In DEB,

APO=90°=BEO. (PERPENDICULAR TANGENT TO RADIUS)

NOW, ADO+BEO+EBC+DAC=360°(SUM OF ANGLE OF QUAD)

CAO=1/2DAC AND CBO=1/2EBC

CAO+CBO=1/2(DAC+EBC)=1/2 X 180°=90°

Now, in tri(AOB),

CAO+AOB+CBO=180°

AOB=180°-(CAO+CBO)=90°

YOUR ANSWER IS 90°