The length of the base of an isosceles triangle is 30m. The angle opposite the
base measures 32° find the perimeter of the triangle to the nearest metre.
We draw the isosceles triangle, letting the two equal sides
be x meters long each:
Now we draw an altitude, which is also a median, a perpendicular bisector
of the base and the bisector of the vertex angle, which cuts the triangle
into two congruent right triangles.
Therefore the 32° angle is cut into two 16° angles and the 30m base is cut
into two 15m segments:
Looking at either of the two congruent right triangles,
Multiply both sides by x
Divide both sides by sin(16°)
Use calculator:
So the 3 sides of the triangle are
30m, 54.41932918m, 54.41932918m
So the perimeter is the sum of the three sides,
or
perimeter = 138.83865836m
To the nearest meter is 139m
Edwin