Q. 16

Mark the correct alternative in the following:

The value of cos (36o – A) cos (36o + A) + cos (54o + A) cos (54o – A) is

A. sin 2 A

B. cos 2A

C. cos 3A

D. sin 3A

Answer :

cos(54o + A) =sin(36o – A)

cos(54o - A) =sin(36o + A)


cos (36o–A) cos (36o+A)+ sin(36o-A)sin(36o+A)=cos(2A)

Rate this question :

How useful is this solution?
We strive to provide quality solutions. Please rate us to serve you better.
Related Videos
Conditional IdentitiesConditional IdentitiesConditional Identities31 mins
Trigonometric Functions - 05Trigonometric Functions - 05Trigonometric Functions - 0568 mins
Trigonometric Functions - 01Trigonometric Functions - 01Trigonometric Functions - 0152 mins
Graphs of trigonometric ratios | Trigonometric IdentitiesGraphs of trigonometric ratios | Trigonometric IdentitiesGraphs of trigonometric ratios | Trigonometric Identities39 mins
Quiz on Graph of Trigonometric RatiosQuiz on Graph of Trigonometric RatiosQuiz on Graph of Trigonometric Ratios40 mins
Trigonometric Functions - 03Trigonometric Functions - 03Trigonometric Functions - 0366 mins
Trigonometric Functions - 06Trigonometric Functions - 06Trigonometric Functions - 0658 mins
Trigonometric SeriesTrigonometric SeriesTrigonometric Series45 mins
Interactive Quiz on trigonometric ratios & identitiesInteractive Quiz on trigonometric ratios & identitiesInteractive Quiz on trigonometric ratios & identities73 mins
Position of a Word & Sum Of NumbersPosition of a Word & Sum Of NumbersPosition of a Word & Sum Of Numbers56 mins
Try our Mini CourseMaster Important Topics in 7 DaysLearn from IITians, NITians, Doctors & Academic Experts
Dedicated counsellor for each student
24X7 Doubt Resolution
Daily Report Card
Detailed Performance Evaluation
caricature
view all courses