How do you find the exact value of sin 105 degrees?
3 Answers
Find exact value of sin (105)
Ans:
Explanation:
sin (105) = sin (15 + 90) = cos 15.
First find (cos 15). Call cos 15 = cos x
Apply the trig identity:
cos 2x = cos (30)
2cos^2 x = 1 + sqrt3/2 = (2 + sqrt3)/2
cos^2 x = (2 + sqrt3)/4
cos x = cos 15 = (sqrt(2 + sqrt3)/2. (since cos 15 is positive)
Check by calculator.
sin (105) = cos 15 = 0.97
Use
Explanation:
sin 45, cos 45 and sin 60 are irrational. So, the answer is a surd.
Explanation:
We know
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