Please help it's argent...!
and also give explanation. thx!

Answers:

a = 63

b = 27

Explanation:

For now, focus on triangle COA.

Since OC and OA are the two radii, this means OC = OA. Furthermore, it means triangle COA is isosceles.

Any isosceles triangle has its base angles congruent to one another. In this case, the base angles are A and C. Both are equal to lowercase 'a'.

So now we know that triangle COA has angles A = a, C = a, O = 54. The three angles of any triangle add to 180

C+O+A = 180

a+54+a = 180

2a+54 = 180

2a = 180-54

2a = 126

a = 126/2

a = 63

Now turn your attention to triangle ABC. This is a right triangle (due to Thales Theorem). The right angle is at angle C, so C = 90.

Use the same idea as before to find b

A+B+C = 180

a+b+90 = 180

63+b+90 = 180

b+153 = 180

b = 180-153

b = 27

answer: 12

step-by-step explanation:

because yes