(6.0 x 10^5) x (3.0 x 10^4) = (6 x 3) x 10^(5 + 4) = 18 x 10^9 = 1.8 x 10^10
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.
Let S be the amount in a savings account.
Let m be the number of months.
General equation
S = 132 + 27m
Specific question
July is the 7th month of the year including both January and July.
S = 132 + 7*27
S = 132 + 189
S = 321
Reasonableness?
Good question. You could estimate an answer.
Start with 150 dollars and say that you add 25 a month.
7 * 25 = 175
S = 150 + 175 = 325 All of this was done in my head. Since the exact answer obtained using the formula is 321, I think that's pretty reasonable using my estimate is a guide.
