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Trigonometry

Lesson 5: Sine and cosine of complementary angles

Relate ratios in right triangles

Consider right triangle triangle, D, E, F below.

Which expressions are equivalent to cosine, left parenthesis, angle, E, right parenthesis?

(Choice A)
start fraction, D, F, divided by, E, F, end fraction
(Choice B)
start fraction, start text, l, e, n, g, t, h, space, o, f, space, s, i, d, e, space, o, p, p, o, s, i, t, e, space, t, o, space, end text, angle, F, divided by, start text, l, e, n, g, t, h, space, o, f, space, h, y, p, o, t, e, n, u, s, e, end text, end fraction
(Choice C)
sine, left parenthesis, angle, F, right parenthesis
(Choice D)
start fraction, D, F, divided by, D, E, end fraction

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