cos(a+贝塔)=1/5,cos(a-贝塔)=3/5,则tanatan贝塔=

cos(a+贝塔)=1/5,cos(a-贝塔)=3/5,则tanatan贝塔=
cos(a+贝塔)=1/5,cos(a-贝塔)=3/5,则tanatan贝塔=

cos(a+贝塔)=1/5,cos(a-贝塔)=3/5,则tanatan贝塔=
解cos（a+β）=cosacosβ-sinasinβ=1/5
cos（a-β）=cosacosβ+sinasinβ=3/5
两式联立解得cosacosβ=2/5,sinasinβ=1/5
故tanatanβ
=(sinasinβ)/(cosacosβ)
=（1/5)/(2/5)
=1/2

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