Answer:
I drew more points as uploaded picture.
We have, arc BD + 210 + 90 = 360 deg
(sum of all arcs on circle)
=> arc BD = 360 - 210 - 90 = 60 deg
Here we have angle CBD = (1/2) x arc CD = (1/2) x 90 = 45 deg
(property of angle on circle)
=> angle ABD = angle ABC - angle CBD = 180 - CBD = 180 - 45 = 135 deg
( A, B, C lie on same line => ABC = 180 deg)
Otherwise, we have:
angle BDA = (1/2) x arc BD = (1/2) x 60 = 30 deg
We have: x + angle BDA + angle ABD = 180 deg
(sum of all angles in a triangle)
=> x = 180 - angle BDA - angle ABD
=> x = 180 -135 - 30
=> x = 15 deg
Hope this helps!
:)
