Question

Triangle ABC and triangle DBC are two isosceles triangle on the same base BC and verticle A and D are

Integration formulae

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(https://www.teachoo.com/3504/753/Ex-11.2--2---Show-line-(1---1--2)--(3--4---2)-is-perpendicular/category/Ex-11.2/) 

But 1st we need to prove that lines are intersecting one's coz in 3d we have skew lines for which angle between lines has no meaning as it can't be found coz they don't intersect

Question pattern in pre primary written test and interview for teacher

BE perpendicular to DA and CD perpendicular to DA then prove that angle 1 = angle 3