Find the slope of the line which makes an angle of 30 with the positive direction of y-axis

Q. No. 7 of Exercise 10.1 of class 11th (Straight Lines)

Find the slope of the line which makes an angle of 30 with the positive direction of y-axis


Sol : 
    
The line OP makes an angle of 30 with y-axis measured anti-clock-wise

Therefore         OP makes an angle of 90+30 = 120 with positive direction of x-axis

Therefore        Slope of OA = tan 120 = tan (180-60)

                                                               =-tan 60 = (3)^1/2