ANALYTIC GEOMETRY PRESENTED BY GUO CHENG GUANG,LIM ZIJIE,GUO CHENGXI(01-05)

1. Finding the points of intersection of perpendicular line. To find the slope of the slope of the perpendicular line, flip the fraction and change the sign. For any linear equation y=mx+b, the perpendiculars will all have a slope of (-1/m), the opposite reciprocal of the original slope.

2. Finding the angle between two line equations.Using α=arctan(m)[Here, α is the angle of inclination, m is the slope. ] and tan(α+β)= [tan(α)+tan(β)]/[1-tan(α)tan(β)]

3. Finding the area of quadrilateral.  Using shoelace formula, suppose the quadrilateral has vertices (x1,y1),(x2,y2),(x3,y3),(x4,y4), listed in clockwise order.

area of quadrilateral =1/2|x1  x2  x3 x4 x1|

                                              |y1  y2  y3 y4 y1|

 =1/2(x1*y2+x2*y3+x3*y4+x3*y1-x2*y1-x3*y2-x4*y3-x1*y4)

ANALYTIC GEOMETRY PRESENTED BY GUO CHENG GUANG,LIM ZI JIE,GUO CHENGXI(01-05,S/N: 5) Presented By Guo Cheng Guang (aged 11), LIM ZI JIE(aged 11) and Guo Chengxi (aged 8) in English. Lessons In Mathematics and Science (Physics, Chemistry and Biology) From Primary to University Presented By Guo Cheng Guang and Guo Chengxi In English. Your comment or suggestion is very much appreciated. https://www.youtube.com/channel/UC2dG5T9SJkUFTy-h0KbVbkw