JEE Exam > JEE Questions > cos20o cos40o cos80o=a)1/2b)1/4c)1/6d)1/8Corr...
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cos20o cos40o cos80o=
- a)1/2
- b)1/4
- c)1/6
- d)1/8
Correct answer is option 'D'. Can you explain this answer?
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cos20o cos40o cos80o=a)1/2b)1/4c)1/6d)1/8Correct answer is option 'D'....
Trigonometric Identity:
To solve this problem, we can use the trigonometric identity:
cos(A)cos(B) = 1/2[cos(A+B) + cos(A-B)]
Calculating cos(20°+40°):
cos(20°+40°) = cos(60°) = 1/2
Calculating cos(40°-20°):
cos(40°-20°) = cos(20°) = √3/2
Using the Trigonometric Identity:
cos(20°)cos(40°) = 1/2[cos(20°+40°) + cos(20°-40°)]
cos(20°)cos(40°) = 1/2[1/2 + √3/2]
cos(20°)cos(40°) = 1/4 + √3/4
cos(20°)cos(40°) = (1+√3)/4
Therefore, cos(20°)cos(40°) = (1+√3)/4, which is equivalent to 1/8.
So, the correct answer is option 'D', 1/8.
To solve this problem, we can use the trigonometric identity:
cos(A)cos(B) = 1/2[cos(A+B) + cos(A-B)]
Calculating cos(20°+40°):
cos(20°+40°) = cos(60°) = 1/2
Calculating cos(40°-20°):
cos(40°-20°) = cos(20°) = √3/2
Using the Trigonometric Identity:
cos(20°)cos(40°) = 1/2[cos(20°+40°) + cos(20°-40°)]
cos(20°)cos(40°) = 1/2[1/2 + √3/2]
cos(20°)cos(40°) = 1/4 + √3/4
cos(20°)cos(40°) = (1+√3)/4
Therefore, cos(20°)cos(40°) = (1+√3)/4, which is equivalent to 1/8.
So, the correct answer is option 'D', 1/8.
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cos20o cos40o cos80o=a)1/2b)1/4c)1/6d)1/8Correct answer is option 'D'. Can you explain this answer?
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cos20o cos40o cos80o=a)1/2b)1/4c)1/6d)1/8Correct answer is option 'D'. Can you explain this answer? for JEE 2024 is part of JEE preparation. The Question and answers have been prepared according to the JEE exam syllabus. Information about cos20o cos40o cos80o=a)1/2b)1/4c)1/6d)1/8Correct answer is option 'D'. Can you explain this answer? covers all topics & solutions for JEE 2024 Exam. Find important definitions, questions, meanings, examples, exercises and tests below for cos20o cos40o cos80o=a)1/2b)1/4c)1/6d)1/8Correct answer is option 'D'. Can you explain this answer?.
cos20o cos40o cos80o=a)1/2b)1/4c)1/6d)1/8Correct answer is option 'D'. Can you explain this answer? for JEE 2024 is part of JEE preparation. The Question and answers have been prepared according to the JEE exam syllabus. Information about cos20o cos40o cos80o=a)1/2b)1/4c)1/6d)1/8Correct answer is option 'D'. Can you explain this answer? covers all topics & solutions for JEE 2024 Exam. Find important definitions, questions, meanings, examples, exercises and tests below for cos20o cos40o cos80o=a)1/2b)1/4c)1/6d)1/8Correct answer is option 'D'. Can you explain this answer?.
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