(a)
A right angle sums to 90
6x + 4x + 10 = 90
10 x = 80
x = 8
(b) straight line = 180
5x + 13 + 3x + 7 = 180
x = 20
(c) Sum of triangle angles = 180
3x + 5 + 2x + 18 + 2x + 17 = 180
x = 20
(d) Sum of two angles in right angle = 90
90 = x + 30
x = 60
Answer:
There is one point: A (x, y) = (2, 0)
Step-by-step explanation:
A point of the square OABC is invariant only if its location coincides with location of the rotation axis, that is, that such point experiments only rotation, no translation in any form. The center of rotation coincides with the location of one of the vertices of the square and, therefore, there is one invariant point on the perimeter: A (x, y) = (2, 0)
The basic angle for 1/2 is 60°, and cosines are negative in the first and third quadrant.
So, you take 180° - 60° = 120° to get the angle in the first quadrant, and 180° + 60° = 240° to get the angle in the third quadrant.
Since only 120° is an option, the answer is
B.
