(sinA-cosA)²=sin²A+cos²A-2sinAcosA=1-2sinAcosA=289/169∴2sinAcosA=-120/169∴sinAcosA=-60/169∴(sin²A+cos²A)/(sinAcosA)=tanA+cotA=（tan²A+1)/tanA=-169/60∴60tan²A+169...