If angle A+angle B +angle C = $${\mathtt{\pi}}$$ (180 degrees) ,$${\mathtt{\pi}}$$-A=B+C
then sinA=sin($${\mathtt{\pi}}$$-A)=sin(B+C)
but A might not equal to B+C, right?
+118677 Mmm
$$\\\pi-A=B+C\;\rightarrow\;A=\pi-(B+C)\\
or\\
A=B+C$$
But I can add 2pi*n to these answers where n is an integer
$$\\A=\pi-(B+C)+2n\pi=(2n+1)\pi-(B+C)\\
or\\
A=B+C +2n\pi$$
Mmm
$$\\A=(2n+1)\pi-(B+C)\\
or\\
A=2n\pi+(B+C)\\\\\\\\
$I think the general formula for this would be$\\
A=(-1)^n(B+C)+n\pi$$
I think that is right but I really need another mathematician to check my working. :))
+752 A+B+C = Pi
B + C = Pi - A
cos(B +C)= cos (Pi -A)
cos (B+C) = -(cos A)
-(cos A) = cos(-A)
so that,
cos(B +C) = cos(-A)
now we cut cos
B+C = -A//
+118677 Mmm
$$\\\pi-A=B+C\;\rightarrow\;A=\pi-(B+C)\\
or\\
A=B+C$$
But I can add 2pi*n to these answers where n is an integer
$$\\A=\pi-(B+C)+2n\pi=(2n+1)\pi-(B+C)\\
or\\
A=B+C +2n\pi$$
Mmm
$$\\A=(2n+1)\pi-(B+C)\\
or\\
A=2n\pi+(B+C)\\\\\\\\
$I think the general formula for this would be$\\
A=(-1)^n(B+C)+n\pi$$
I think that is right but I really need another mathematician to check my working. :))
