1)cost/(1+cost)+cost/(1-sint)=((cost(1-sint+1+sint))/(1+sint)*(1-sint)=2cost/cos^2t=2/cost
2)tqx+1/(1-ctqx)=1/ctqx+1/(1-ctqx)=(1-ctqx+ctqx)/(ctqx(-ctqx)=1/(ctqx-ctq^2x)
1. D=1-4*1*(-2)=9
2. x=2+3/2=5/2
x=2-3/2= -1/2
(12a-1)/2-1= 6a-1/2 - 1=6a-1.1/2(2a+6b)/2-24ab=a+3b-24ab
121-(11-9x)2=121-22+18x=99+18x
a/2b/2-(ab-7)/2=a/b-ab/2+7/2
b/2+49-(b-7)/2=b/2+49-b/2+7/2=52.1/2
a/4-81-(a/2+9)/2=a/4-81-a/4-9/2=-85.1/2