The equations of the lines through $(1,\,1)$ and making angles of $45^{\circ}$ with the line $x+y=0$ are

Find the acute angle between the lines $3x + y -7 = 0$ and $x + 2y- 9 = 0.$

ABC triangle have three points are$A ( 3 , - 1 ) , B ( 2,3 )$ and C $= ( 5,1 ) ,$ then $\angle A =$?

The angle between the pair of lines whose equation is $4{ x }^{ 2 }+10xy+m{ y }^{ 2 }+5x+10y=0$ is

4x – y + 5 = 0 এবং 9x - 2y - 12 = 0 রেখা দুইটির মধ্যবর্তী কোণ θ হলে tanθ এর ধনাত্মক মান কত?