Question

Please solve question 19.

Answer 1

Solution is in the pic.
$ao = oc \: as \: they \: are \: radii \:$
Answer is 25°.

Answer 2

let angle ACO be x therefore angle OAC=x (angles opp.to equal sides in triangle ACO)
in triangle COT
angle TCO=90(radius us perpendicular to the tangent)
therefore in triangle TCO
angleTOC+90+40=180(angle sum property)
therefore angle TOC=180-130=50

in triangle ACO
x+x=50( exterior angle =sum of two opposite interior angles)
therefore X=25
angle ACO=25


I hope this will help