Question
sir EX 1.2,5 For checking onto given there is no pre imagefor y=2, y=100 etc..but in signum functions its domain is 1 https://www.teachoo.com/3914/1163/Ex-1.2--5---Show-Signum-Function-is-neither-one-one-nor-onto/category/To-prove-injective--surjective--bijective-(one-one---onto)/mage for y=2
In triangle ABC, D AND E ARE THE POINTS ON THE SIDE AB AND AC RESPECTIVELY SUCH THAT DE//BC, IF AD=6X-7, DB=4X-3, AE=3X - 3 AND EC=2X-1,THEN FIND THE VALUE OF X
I am looking for the proof of the theorem that the included angle(s) in a semicircle is (are) right angle(s). I thought this was "Thales Theorem" . Theorem 6:1 here, is marked as referring to Thales but is about basic proportionality (a line parallel to the base of a triangle cuts the other 2 sides in the same proportion)
The proof on the Wolfram site uses scalar vectors which I don't (yet) understand and also ( I think) has a slight error , or misprint, in the explanation.