Answer:
The value of radius is 7.5 units
Step-by-step explanation:
Given that a line that pass through the origin and form a triangle is a right-angle triangle. So in order to find the diameter/hypotenuse, you have to use Pythogaras Theorem :

Let a = 12 units,
Let b = 9 units,
Let c = hypo.,




We have found out that the hypotenuse of the triangle is the diameter of circle. So in order to find radius, you have to divide it by 2 :



Answer:
∠ACB = 38°
Step-by-step explanation:
∠ACB is an inscribed angle while arcAB is its intercepted arc
An inscribed angle is equal to half the length of its intercepted arc
Hence, ∠ACB = 1/2 the measure of arc AB
arc AB = 76°
Hence ∠ACB = 1/2 of 76
76/2 = 38
Therefore ∠ACB = 38°
I'm sorry, but I don't understand ;-;
There’s an invisible 1 in front of the minus sign and an invisible 1 in front of the variable.
-1(r+4)=-3 —> -1 times 1r = -1r. -1 times 4 = -4
Multiply inside the parentheses.
-1r-4=-3
Now add 4 to both sides.
-1r-4=-3
+4=+4
-1r = 1
Now divide
R= -1
1.754
Because without the decimal 54 is more than 48 (a little trick I used)