Question

Find the obtuse angle between the straight lines 9x+3y-4=0 and 2x+4y+5=0.

Answer 1

I don't no your questions

Answer 2

9x+3y-4=0----- (1)

2x+4y+5=0------- (2)

from equation (1)

slope of line = -9/3 = -3 = m1

from equation (2)

slope of line = -2/4 = -1/2 = m2

then , tan theta = mod of m1-m2 /1+m1×m2

= mod of -3+1/2 / 1-3×-1/2

= mod of -1 = 1

tan theta = 1

theta = 135° ( because in question to find obtuse angle , so , tan 135° = -1 )

Thanks