sin(a+b)cos(a-b)=sinacosa+sinbcosb_数学解答

sin(a+b)cos(a-b)=sinacosa+sinbcosb

人气：235 ℃　时间：2020-06-14 16:49:49

解答

sin(a+b)cos(a-b)=(sinacosb+cosasinb)(cosacosb+sinasinb)=sinacosa(cosb)^2+(cosa)^2sinbcosb+(sina)^2sinbcosb+sinacosa(sinb)^2=sinacosa(cosb)^2+sinacosa(sinb)^2+(cosa)^2sinbcosb+(sina)^2sinbcosb=sinacosa...