The circle below is centered at the point (4,3) and has a radius length 5. What is its equation
2 answers:
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Answer:
see below
Step-by-step explanation:
A. Reflection across the y-axis replaces each x coordinate with its opposite.
B. Rotation 90° CW does the transformation (x, y) ⇒ (y, -x)
C. This is a translation left 2 units.
D. Rotation 90° CCW does the transformation (x, y) ⇒ (-y, x)
E. This is a translation left 7 and down 2.
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In the attached graphs, we have identified a point that is a corresponding point on each figure. This is so you can see how the various transformations move it and the rest of the figure in relation to it. 90° arcs are shown so you can see the rotations more easily.
The figures are labeled and color coded in accordance with the problem statement.
9514 1404 393
Answer:
D
Step-by-step explanation:
In the second quadrant, ...
c = 180° -arcsin(24/25) ≈ 106.26°
In the third quadrant, ...
d = 360° -arccos(-3/4) ≈ 221.41°
Then cos(c+d) = cos(327.67°) ≈ 0.84498
This is a positive irrational number, greater than 21/100, so the only reasonable choice is the last one:
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Perhaps you want to work this out using the trig identities.
cos(c) = -√(1 -sin(c)²) = -7/25
sin(d) = -√(1 -cos(d)²) = -(√7)/4
Then the desired cosine is ...
cos(c+d) = cos(c)cos(d) -sin(c)sin(d)
cos(c+d) = (-7/25)(-3/4) -(24/25)(-√7/4)
cos(c+d) = (21 +24√7)/100 . . . . matches choice D