Posted by ...wew on .
Find the altitude of an isosceles triangle whose base in 30 cm vertex angle is 75 degres

trig 
Reiny,
draw the altitude,
I see a rightangled triangle with base 15 and base angle of 52.5°
Call the height h
h/15 = tan 52.5
h = 15tan 52.5
= ....
I will let you do the buttonpushing.