O is the centre of the circle, EF is a tangent, angle BCE=28 degrees, angle ACD=31 degrees. Line AB = Line AC.

Write down the size of
a. angle BAC
b. angle ABC
c. angle ADC
d. angle COB

a. 28˚

b. 76˚

c. 104˚

d. 56˚

Step-by-step explanation

a. because angle between tangent and chord is equal to the angle(s) in alternate segment.

b. because angles in triangles add up to 180˚, 180-28=152 and because isosceles triangle, 152/2=76˚

c. because angles in triangles add up to 180˚ and opposite angles in a cyclic quadrilateral add up to 180˚, 31+76=107, 180-107=73, 73-28=45, angles in triangle so 180-(31+45)=104˚

d. 28*2=56˚ because angles at circumference are half angles at centre

both equations and proportions are better.

answer: what are the following choices