Question

How to do the 51st question ?

Answer 1

see diagram.

We know that the tangents drawn to a circle from a point are equal. They form congruent triangles formed by the points of contact and the center.  For example, angles OBA and angle OBC are equal.

Let angles OBA = OBC = x.. then OAB = OAD = 55 - x deg.

Let angle COB = y.  Let angle COD = z.

    Then angle OCB = angle OCD = 180-x-y..

             Angle ODC = angle ODA = x+y-z...

Sum the angles in triangle OAD to get:

      290 - 2z = 180,  ie, 110 = 2z.

So z = angle COD = 55 deg.

Answer 2

Answer:

I will have to check with my husband about the other one better send kar