Respuesta :

AC is a tangent so by definition, it touches the circle at exactly one point (point C) and forms a right angle at the tangency point. So angle ACO is 90 degrees

The remaining angle OAC must be 45 degrees because we need to have all three angles add to 180
45+45+90 = 90+90 = 180

Alternatively you can solve algebraically like so
(angle OAC) + (angle OCA) + (angle COA) = 180
(angle OAC) + (90 degrees) + (45 degrees) = 180
(angle OAC) + 90+45 = 180
(angle OAC) + 135 = 180
(angle OAC) + 135 - 135 = 180 - 135
angle OAC = 45 degrees

Side Note: Triangle OCA is an isosceles right triangle. It is of the template 45-45-90. 
abidemiokin

The measure of m<OAC is 45degrees

Tangent line to a circle

From the given diagram, we can see that the line A is tangential to the circle at point C, hence m<C = 90 degrees

Taking the sum of angle in a triangle

m<OAC + 45 + 90 = 180

m<OAC = 180 - 135

m<OAC = 45 degrees

Hence the measure of m<OAC is 45degrees

Learn more on circle geometry here: https://brainly.com/question/25306774

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