Q.

Let α and β be real numbers such that π4<β<0<α<π4. If  sin(α+β)=13 and cos(αβ)=23, then the greatest integer less than or equal to (sinαcosβ+cosβsinα+cosαsinβ+sinβcosα)2 is 

see full answer

Start JEE / NEET / Foundation preparation at rupees 99/day !!

21% of IItians & 23% of AIIMS delhi doctors are from Sri Chaitanya institute !!
An Intiative by Sri Chaitanya

answer is 1.

(Unlock A.I Detailed Solution for FREE)

Ready to Test Your Skills?

Check your Performance Today with our Free Mock Test used by Toppers!

Take Free Test

Detailed Solution

detailed_solution_thumbnail

Given,  si(α+β)=13
And  cos(αβ)=23
Let,  E=sinαcosβ+cosβsinα+cosαsinβ+sinβcosα
=sinαsinb+cosαcosβsinβcosβ+cosαcosβ+sinαsinβsinαcosα

=cos(αβ)sinβcosβ+cos(αβ)sinαcosα

=cos(αβ)[22sinβcosβ+2sinαcosα]         =cos(αβ)[22sinβcosβ+22sinαcosα]        =23[2sin2β+2sin2α]           =43[1sin2β+1sin2α]        =43[sin2α+sin2βsin2αsin2β]       =4×23[2sin(2α+2β2)cos(2α2β2)2sin2αsin2β]           =163[sin(α+β)cos(αβ)cos(2α2β)cos(2α+2β)]         =163[13×23(2cos2(αβ)1)(12sin2(α+β))]           =3227[12×492+2×19]           =3227[9818+2]         =3227[9818+2]  =3227[98]          =43                     E2=169=1.77                        [E2]=1

Watch 3-min video & get full concept clarity
score_test_img

Get Expert Academic Guidance – Connect with a Counselor Today!

whats app icon