Given equation of straight line is 3x+3y+5=0 ⇒‌‌3x+3y=−5 ⇒‌‌−3x−3y=5 Now, for converting this equation in normal form. Divide by √(−3)2+(−3)2=3√2 on both sides, we get ‌
−3
3√2
x−‌
3
3√2
y=‌
5
3√2
⇒‌‌−‌
1
√2
x−‌
1
√2
y=‌
5
3√2
Compare with x‌cos‌α+y‌sin‌α=p, we get cos‌α=sin‌α=−‌