Geometry and TrigonometryHardComplementary angle identity
Geometry and Trigonometry practice question
In right triangle DEF, angle F is the right angle and the measure of angle D is 50°. Which of the following is equal to sin E?
- A. cos 50°Correct
- B. sin 50°
- C. cos 40°
- D. tan 40°
Answer: A. cos 50°
Angle E measures 40°, and sin 40° = cos 50° because the two angles are complementary.
Why the other answers are wrong
- B. sin 50°
- sin 50° is sin D, not sin E.
- C. cos 40°
- cos 40° equals sin 50°, not sin 40°.
- D. tan 40°
- tan 40° is a different ratio.
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