1.若cos x=5/13 及tan(x+y)= -120/119,其中x及y为锐角.证明x=y.

1.若cos x=5/13 及tan(x+y)= -120/119,其中x及y为锐角.证明x=y. 1.sin x-cos x=负跟号5/2,则tan x+1/tan x的值 2.(1-cos x)(1/sin x+1/tan x)= 5cos(x-y/2)+7cos(y/2)=0求tan(x/2)*tan[(x-y)/2] 为什么cos(sin(tan x)))=1 已知 SIN@+COS@=3 (90度小于@x小于180度0,求SIN@-COS@ 及 TAN@的值 tan(x)=2求sin(x)cos(x)=? tan x=2,求 sin x * cos x=? 求证：tan x/2=sin x/(1+cos x) 求证：1-sin(x)=cos(x)*tan(x/2) (tan x+cot x)cos平方x= 若x属于零到六分之派,比较tan(tan x),tan(cos x),tan(sin x)的大小并证明 1/cos(x) - tan(x) = 3 求sin(x)1/cos(x) - tan(x) = 3求sin(x) 1.已知tan x=负2,则1/4sin x 平方+2/5cos x的平方=? 已知:tan x=2 求:sin x+cos x/sin x-cos x=? 已知tan=2,求(cos x+sin x)/(cos x-sin x)+sin^2x 若tanα=m 则sin(-5π-α)cos(3x+α）= (sin x) + (cos x) = (tan x) + 1/(tan x)0 sin x+cos x=7/13 求tan x=?