Lượng Giác

L

lovelycat_handoi95

[TEX](1+sinx)(sinx+4cosx-7)+3(2-cosx)^2=0 \\ \Leftrightarrow (sinx+1)[(sinx+1)-4(-cosx+2)]+3(2-cosx)^2=0 \\ Dat : sinx+1 =a & 2-cosx= b \\ PT \Leftrightarrow a(a-4b)+3b^2 = 0 \\ \Leftrightarrow a(a-b) - 3b(a-b) = 0 \\ \Leftrightarrow \left[ a=b \\ a= 3b [/TEX]

[TEX] \Leftrightarrow \left[sinx+cosx=1 \\ sinx+3cosx=5 [/TEX]
 
Last edited by a moderator:
You must log in or register to reply here.
Top Bottom