Cos (x + y) Formula | Trigonometry Identity Explained with Easy Trick | Class 11| Ncert Math

Learn the most important trigonometric identity: cos (x + y) = cos x cos y – sin x sin y in a simple and clear way. This video explains the derivation, shortcut memory trick, and solved examples for JEE Mains, JEE Advanced, and Class 11–12 students. Master angle addition formulas to score full marks in Trigonometry! #trigonometry #maths #class11maths #jee2026 #cosxplusy #angleadditionformula #iitpreparation #class11maths #formulatricks #studywithme #mathematics #jeemains #jeeadvanced #mathformula #trigonometryidentity #cbseclass11 #cbseclass12 #boards2026 #engineeringentrance #mathstricks #competitiveexams