两角和与差的三角函数 (19 20:44:12)已知tana=-3/4 _数学解答

两角和与差的三角函数 (19 20:44:12)
已知tana=-3/4 180度

人气：388 ℃　时间：2020-02-03 18:41:57

解答

tan(60度-A)
=(tan60-tanA)/(1+tan60tanA)
=(√3+3/4)/(√3-3/4)
=[(4√3+3)/4]/[(4√3-3)/4]
=(4√3+3)/(4√3-3)
=(4√3+3)^2/[(4√3-3)(4√3+3)]
=(57+24√3)/39
=(19+8√3)/13