If cos-13/5- sin-14/5 = cos-1x then x = a.0 b.1 c.-1 d.2 Share with your friends Share 0 Manbar Singh answered this We have,cos-135 - sin-145 = cos-1xLet cos-135 = α and sin-145 = β⇒cos α = 35 and sin β = 45⇒sin α = 1-cos2α and cos β = 1-sin2β⇒sin α =1-925 and cos β = 1-1625⇒sin α =1625 and cos β =925⇒sin α = 45 and cos β = 35cosα - β = cos α . cos β + sin α . sin β⇒coscos-135 - sin-145 = 35×35+45×45=925+1625 = 2525 = 1⇒cos-135 - sin-145 = cos-11 ........1but, cos-135 - sin-145 = cos-1x ..........2comparing 1 and 2, we getx = 1 1 View Full Answer
