1.若cos A+cosB=1/2,sinA+sinB=1/3,则cos (A-B)= A.--59/72 B.--59/36 C.--13/72 D.59/362.在锐角三角形ABC中,设x=sinAsinB,y=cosAcosB,则x,y的大小关系?A.x≤y B.x>y C.x<y D.x≥y3.若(4tan A+1)(1-4tanB)=17,则tan(A-B)= A.1/4 B
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![1.若cos A+cosB=1/2,sinA+sinB=1/3,则cos (A-B)= A.--59/72 B.--59/36 C.--13/72 D.59/362.在锐角三角形ABC中,设x=sinAsinB,y=cosAcosB,则x,y的大小关系?A.x≤y B.x>y C.x<y D.x≥y3.若(4tan A+1)(1-4tanB)=17,则tan(A-B)= A.1/4 B](/uploads/image/z/1833932-20-2.jpg?t=1.%E8%8B%A5cos+A%2BcosB%3D1%2F2%2CsinA%2BsinB%3D1%2F3%2C%E5%88%99cos+%EF%BC%88A-B%29%3D+A.--59%2F72+B.--59%2F36+C.--13%2F72+D.59%2F362.%E5%9C%A8%E9%94%90%E8%A7%92%E4%B8%89%E8%A7%92%E5%BD%A2ABC%E4%B8%AD%2C%E8%AE%BEx%3DsinAsinB%2Cy%3DcosAcosB%2C%E5%88%99x%2Cy%E7%9A%84%E5%A4%A7%E5%B0%8F%E5%85%B3%E7%B3%BB%3FA.x%E2%89%A4y+B.x%EF%BC%9Ey+C.x%EF%BC%9Cy+D.x%E2%89%A5y3.%E8%8B%A5%EF%BC%884tan+A%2B1%EF%BC%89%EF%BC%881-4tanB%EF%BC%89%3D17%2C%E5%88%99tan%EF%BC%88A-B%29%3D+A.1%2F4+B)
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