Ask a Doubt
Request a call back

Join NOW to get access to exclusive study material for best results

CBSE Class 11-science Answered

Evaluate : 16cos (2π/15) cos (4π/15) cos (8π/15) cos (16π/15)
Asked by tps.mjmdr | 16 Jun, 2018, 05:50: PM
answered-by-expert Expert Answer
begin mathsize 16px style 16 cos open parentheses fraction numerator 2 straight pi over denominator 15 end fraction close parentheses cos open parentheses fraction numerator 4 straight pi over denominator 15 end fraction close parentheses cos open parentheses fraction numerator 8 straight pi over denominator 15 end fraction close parentheses cos open parentheses fraction numerator 16 straight pi over denominator 15 end fraction close parentheses equals 16 cos open parentheses fraction numerator 2 straight pi over denominator 15 end fraction close parentheses cos open parentheses fraction numerator 4 straight pi over denominator 15 end fraction close parentheses cos open parentheses fraction numerator 8 straight pi over denominator 15 end fraction close parentheses cos open parentheses straight pi plus straight pi over 15 close parentheses equals negative 16 cos open parentheses fraction numerator 2 straight pi over denominator 15 end fraction close parentheses cos open parentheses fraction numerator 4 straight pi over denominator 15 end fraction close parentheses cos open parentheses fraction numerator 8 straight pi over denominator 15 end fraction close parentheses cos open parentheses straight pi over 15 close parentheses equals fraction numerator negative 8 over denominator sin straight pi over 15 end fraction cross times 2 sin straight pi over 15 cos open parentheses straight pi over 15 close parentheses cos open parentheses fraction numerator 2 straight pi over denominator 15 end fraction close parentheses cos open parentheses fraction numerator 4 straight pi over denominator 15 end fraction close parentheses cos open parentheses fraction numerator 8 straight pi over denominator 15 end fraction close parentheses equals fraction numerator negative 8 over denominator sin straight pi over 15 end fraction cross times sin open parentheses fraction numerator 2 straight pi over denominator 15 end fraction close parentheses cos open parentheses fraction numerator 2 straight pi over denominator 15 end fraction close parentheses cos open parentheses fraction numerator 4 straight pi over denominator 15 end fraction close parentheses cos open parentheses fraction numerator 8 straight pi over denominator 15 end fraction close parentheses equals fraction numerator negative 4 over denominator sin straight pi over 15 end fraction cross times 2 sin open parentheses fraction numerator 2 straight pi over denominator 15 end fraction close parentheses cos open parentheses fraction numerator 2 straight pi over denominator 15 end fraction close parentheses cos open parentheses fraction numerator 4 straight pi over denominator 15 end fraction close parentheses cos open parentheses fraction numerator 8 straight pi over denominator 15 end fraction close parentheses equals fraction numerator negative 2 over denominator sin straight pi over 15 end fraction cross times 2 sin open parentheses fraction numerator 4 straight pi over denominator 15 end fraction close parentheses cos open parentheses fraction numerator 4 straight pi over denominator 15 end fraction close parentheses cos open parentheses fraction numerator 8 straight pi over denominator 15 end fraction close parentheses equals fraction numerator negative 2 over denominator sin straight pi over 15 end fraction cross times sin open parentheses fraction numerator 4 straight pi over denominator 15 end fraction close parentheses cos open parentheses fraction numerator 4 straight pi over denominator 15 end fraction close parentheses cos open parentheses fraction numerator 8 straight pi over denominator 15 end fraction close parentheses equals fraction numerator negative 1 over denominator sin straight pi over 15 end fraction cross times 2 sin open parentheses fraction numerator 8 straight pi over denominator 15 end fraction close parentheses cos open parentheses fraction numerator 8 straight pi over denominator 15 end fraction close parentheses equals fraction numerator negative 1 over denominator sin straight pi over 15 end fraction cross times sin open parentheses fraction numerator 16 straight pi over denominator 15 end fraction close parentheses equals fraction numerator negative sin open parentheses straight pi plus begin display style straight pi over 15 end style close parentheses over denominator sin straight pi over 15 end fraction equals fraction numerator sin straight pi over 15 over denominator sin straight pi over 15 end fraction equals 1 end style
Answered by Sneha shidid | 18 Jun, 2018, 10:46: AM

Concept Videos

Multiple Choice Questions Practice Test
Answered Unanswered My Questions My Answers
CBSE 11-science - Maths
Prove that 2sin^2 y + 4cos(x + y) sinxsiny ny + cos 2 * (x + y) = cos 2x
Asked by apnp31 | 21 Sep, 2020, 12:19: PM
ANSWERED BY EXPERT ANSWERED BY EXPERT
CBSE 11-science - Maths
Cos5π/4-sin5π/4+tan11π/4-cot11π/4? SIn4530°? Cos (-9π/4)? Sin 120°cos 150°-cos240°sin330°? If tan35°=k then,Tan145°-Tan125°/1+Tan145°.Tan125°?
Asked by Pallapothu.a | 05 Aug, 2020, 04:13: PM
ANSWERED BY EXPERT ANSWERED BY EXPERT
CBSE 11-science - Maths
clear my doubt
question image
Asked by kandukuriPraneeth16 | 25 Jul, 2020, 06:18: PM
ANSWERED BY EXPERT ANSWERED BY EXPERT
CBSE 11-science - Maths
trigonometry ka question hai please solve
question image
Asked by jaiswalpiyush040 | 20 Jul, 2020, 08:22: AM
ANSWERED BY EXPERT ANSWERED BY EXPERT
CBSE 11-science - Maths
Prove that cos^2 pi/8 + cos^2 3pi/8 + cos^2 5pi/8 + cos^2 7pi/8 =2  
Asked by anushkapanwar74 | 15 Aug, 2019, 01:26: PM
ANSWERED BY EXPERT ANSWERED BY EXPERT
CBSE 11-science - Maths
2 tan B + cot B = tan A , show that 2 tan(A-B) = cot B
Asked by agarwalharsh8476 | 06 Aug, 2019, 08:32: PM
ANSWERED BY EXPERT ANSWERED BY EXPERT
CBSE 11-science - Maths
sinx1sinx2-cosx1cosx2+1=0 the value of tanx1/2*tanx2/2 is alwya equal to?  
Asked by aahnik.mohanty | 29 May, 2019, 08:00: PM
ANSWERED BY EXPERT ANSWERED BY EXPERT
CBSE 11-science - Maths
For any real x find the minimum and maximum value for the expression 3sin^2x +3sinxcosx + 7cos^2x.
Asked by acv27joy | 10 Dec, 2018, 01:10: PM
ANSWERED BY EXPERT ANSWERED BY EXPERT
CBSE 11-science - Maths
If sin x + cos x = sqrt{y+(1/y)} such that x belongs to [0,6Π] and y>0 prove that x = Π/4 or 9Π/4.
Asked by acv27joy | 08 Oct, 2018, 09:42: AM
ANSWERED BY EXPERT ANSWERED BY EXPERT
CBSE 11-science - Maths
(sinø-cosø)^2=1-sin2ø
Asked by abhaysharma2710 | 15 Jul, 2018, 10:09: AM
ANSWERED BY EXPERT ANSWERED BY EXPERT
My Class Videos Tests ₹ Plans Ask a Doubt
Get Latest Study Material for Academic year 24-25 Click here
×