A.Maths,,Help急急急

5sin^2 x-3sinxcosx-2cos^2x=0

( 5sinx+2cosx)(sinx-cosx)=0

5sinx+2cosx=0 or sinx-cosx=0

5sinx=-2cosx or sinx=cosx

tanx=-2/5 or tanx=1

x=158.2*,338.2* or 45* or 225*


2007-11-21 23:23:00 補充：
Formula used: sinx / cosx = tanxReminder: In the 1st quad., all +VE, 2nd quad., sin +VE, 3rd quad., tan +VE, 4th quad. , cos +VE

5 Sin^2 x - 3SinxCosx - 2Cos^2 x = 0
divide by Cos^2 x gives
5Tan^2 x -3Tanx-2=0
(5Tanx+2)(Tanx-1)=0

5Tanx+2 = 0 or Tanx -1 =0

Tan x = -2/5 or Tan x =1

for 0<360

Tan x = -2/5
x = 158.2 degrees (2nd Quadrant) or 338.2 degrees (4th Quadrant)

Tan x =1
x = 45 degrees (1st quadrant) or 225 degrees (3rd Quadrant)