Anna und Chiara wohnen 18km
voneinander entfernt. Sie fahren
einander entgegen Chiara mit 18km/h;
Anna fährt eine halbe Stunde später mit
18km/h
a) Wie lange braucht Chiara zum
Treffpunkt.
b) Welcher Strecke hat Anna
zurückgelegt?

Okay so for every triangle has three angles that always add up to 180 degrees. and to tell the difference between whether they are secure, right or obtuse is that acute: has one angle that is less than 90 degrees. right triangle means there is at least one angle that is exactly 90 degrees. and an obtuse angle has an angle that is bigger than 180 degrees. i’ll do #13 as an example: 13. 40 and 50 so if every triangle has 180 degrees 40+50= 90 degrees then180-90= 90 degrees so the third angle is 90 degrees and because this triangle has a 90 degree angle it means it is a right triangle