Question

Help Geometry!!
AC is tangent to circle O at A. If , m<BY= 24 , what is m<YAC?

a) 48

b) 156

c) 78

d) 132

Answer 1

we know that
The inscribed angle measures half of the arc it comprises.
so
∡BAY=BY/2------> 24/2------> 12°

angles YAC and BAY are complementary angles
∡YAC+∡BAY=90°
∡YAC=90-∡BAY-------> ∡YAC=90-12-----> 78°

the answer is
78°