The given pair of straight lines is ‌ax2+2hxy+by2=0 . . . (i) ‌∴‌‌m1+m2=‌
−2h
b
‌‌ and ‌‌m1m2=‌
a
b
‌‌ Here, ‌‌m1=tan‌45∘=1 Then, the equation of the line is y=x. We have, ⇒‌ax2+2hx2+bx2‌=0 ⇒‌a+2h+b‌=0 ⇒‌a+b‌=−2h (a+b)2‌=4h2