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Cos x + cos y formula
Ex 3.3, 11 Important
Misc 3
Misc 4 Important
Ex 3.3, 14
Ex 3.3, 15
Misc 5
Misc 7 Important
Example 16 Important
Ex 3.3, 16 Important
Ex 3.3, 17
Ex 3.3, 18 Important You are here
Ex 3.3, 19
Ex 3.3, 20
Ex 3.3, 21 Important
Example 17 Important
Misc 6 Important
cos x + cos y formula
Last updated at May 29, 2023 by Teachoo
Ex 3.3, 18 Prove that 〖sin x − 〗siny /(𝑐𝑜𝑠x + 𝑐𝑜𝑠y ) = tan (x − y)/2 Solving L.H.S 〖sin x − 〗siny /(𝑐𝑜𝑠x + 𝑐𝑜𝑠y ) = 〖2 𝑐𝑜𝑠((𝑥 + 𝑦 )/2)〗〖 𝑠𝑖𝑛((𝑥 − 𝑦 )/2) 〗/(2 𝑐𝑜𝑠((𝑥 + 𝑦 )/2) 𝑐𝑜𝑠((𝑥 − 𝑦 )/2) ) We Know that sin x – sin y = 2 cos ((𝑥 + 𝑦 )/2) sin ((𝑥 − 𝑦 )/2) & cos x + cos y = 2 cos ((𝑥 + 𝑦 )/2) cos ((𝑥 − 𝑦 )/2) = 𝑠𝑖𝑛" " ((𝑥 − 𝑦 )/2)/(𝑐𝑜𝑠((𝑥 − 𝑦 )/2) ) = tan (𝑥 − 𝑦 )/2 = R.H.S Hence L.H.S. = R.H.S. Hence proved