Find the area of isosceles triangle whose base is 15 cm and vertical angle is 80 degree

Question

Find the area of isosceles triangle whose base is 15 cm and vertical angle is 80º

Answer 1

??????????????????? "vertikal angel" ??????????????

me assume yu meen angel at the top=80 deg

and the base =horizontal line at botton (kros from the top angel)

eech base angel=(180-80)/2=50 deg

draw vertikal line from top tu base & yu get rite triangel & hite is 1 side av it

Its base=15/2=7.5

tan(40 deg)=(7.5/hite), so hite=7.5/tan(40 deg)

hite=7.5 / 0.839099631=7.5*1.191753593=8.938151944

triangel area=(1/2)hite*base=hite*(base/2)=8.938151944*7.5

area=67.03613958