# Misc 13 - Chapter 10 Class 11 Straight Lines

Last updated at May 29, 2018 by Teachoo

Last updated at May 29, 2018 by Teachoo

Transcript

Misc 13 Show that the equation of the line passing through the origin and making an angle with the line y = mx + c is / = ( )/(1 ) . Let OP be the line passing through origin Let PQ be the line y = mx + c Whose slope is m and makes an angle with line OP We need to show equation line OP is / = ( )/(1 ) We know that equation of line passing through point(x1, y1) & having slope m is (y y1) = m(x x1) Let m1 be the slope of line OP Equation of a line OP passing through origin (0, 0) with slope m1 (y 0) = m1(x 0) y = m1x Now we need to find slope (i.e. m1) of line OP It is given that line OP makes an angle with line PQ y = mx + c Angle between two line whose slope are m1 & m2 is tan = |( _2 _1)/(1 + _2 _1 )| Angle between line OP & PQ is tan = |( _1 )/(1 + _1 )| |( _1 )/(1 + _1 )| = tan ( _1 )/(1 + _1 ) = tan So, ( _1 )/(1 + _1 ) = tan & ( _1 )/(1 + _1 ) = tan Hence, m1 = ( + tan )/(1 m tan ) and m1 = ( tan )/(1 + m tan ) m1 = ( tan )/(m m tan ) Putting value of m1 in (1) y = ( tan )/(m m tan ) / = ( tan )/(m m tan ) Hence proved

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Davneet Singh

Davneet Singh is a graduate from Indian Institute of Technology, Kanpur. He has been teaching from the past 8 years. He provides courses for Maths and Science at Teachoo. You can check his NCERT Solutions from Class 6 to 12.