Find the perimeter of an isosceles triangle whose base is 40 cm and whose base angle is 70o
since the triangle is isosceles, the other two sides will have equal length. Let call the length of each side "x" .
Draw a perpendicular from vertex to base
(Bisector of base)
You will get a right triangle with a leg "20 cm" and one angle "70 degrees"
Hence can use "cosine" "ratio" to obtain other side.
"cos(70\u00b0)=\\frac{20}{x}"
"x=\\frac{20}{cos(70\u00b0)}=58.48cm"
Add up the sides to get perimeter
Perimeter "= 58.48+58.48+40=156.96"
Comments
Leave a comment