Sorry, it's late, and I'm a bad explainer.
The error is adding (2x-12) with x and 30. This is wrong because you are adding the angles inside the triangle and you are assuming that (2x - 12) is the unlabeled angle INSIDE the triangle, when it is the exterior angle/outside of the triangle.
A straight line is also 180°.
(2x - 12) + ? = 180
30 + x + ? = 180
If you look at the equations, and put parentheses around 30 + x, (30 + x) and (2x - 12) should be the SAME NUMBER. So you could set them equal to each other to find x. (or you could also look at the picture and see that they both need/are missing the same angle)
2x - 12 = 30 + x
x = 42
Now you plug 42 into the exterior angle equation
2(42) - 12 = 84 - 12 = 72°
Answer:
x - 4 = 0 and x - 2 = 0
Step-by-step explanation:
Answer:
pi × 18cm^2
Or approximately,
56.52cm^2 (using 3.14 for pi)
or
56.5487cm^2 (using pi button on calculator)
Step-by-step explanation:
Area of a circle is pi times [radius squared].
All circles are 360°.
Problem can be solved by finding area of whole circle, and then using ratios.
Whole Circle: area = pi × (9cm)^2 = pi × 81cm^2
80° / 360° = Area[shaded] / (pi × 81cm^2)
pi × 18cm^2 = Area[shaded]
((If you read my answer before the edit, I am sorry. I made a calculator error.))
