Do you know how to do this problem?
cos #((13pi)/"12")#
cos
1 Answer
Apr 23, 2018
Formula:-
#"(1) "cos(pi+theta)=-costheta#
#" (2) "cos2theta=2cos^2theta-1# Problem:-
#darr#
#cos((13pi)/12)#
#=cos(pi+pi/12)#
#=-cos(pi/12)#
#=-sqrt((1+cos(pi/6))/2)#
#=-sqrt((1+sqrt3/2)/2#
#=-sqrt(1/2+sqrt3/4#
#=- 1/4sqrt(8+4sqrt3)#
#=- 1/4sqrt((sqrt6+sqrt2)^2#
#=- 1/4(sqrt6+sqrt2)# Hope this helps...
Thank you...
:-)
