اكس =

-1-

-2-

X=360-(90+140+60)

X=360-290

X=70

------------------------------

 tan(a+b)=(tan a. +tan b)/(1-tana×tan b)

=(1/3+1/2)/(2/1×1-1/3)= 1

a+b=45

tan c=1

C=45

a+b+c=90

---------

40

-3-

-4-