Question

已知,在△ABC中,∠ACB=90°,D为AB中点,若tan∠BCD=三分之一,求∠A的三角函数值

Answer 1

在△ABC中,∠ACB=90°,D为AB中点

=> CD = AD = BD,∠BCD =∠B

tan∠BCD = 1/3,

=> tan∠B = 1/3,cot∠B = 3,sin∠B = 3/√10,cos∠B = 1/√10

=> tan∠C= 3,cot∠C = 1/3,sin∠C = 1/√10,cos∠B = 3/√10