The perimeter is the sum of all sides' lengths
So the perimeter = 4*160 m =640 m = 0.64 km
18,264,947,048,470
there ya go
In the third quadrant, the tangent is positive.
tan(θ) = tan(arcsin(0.7660)) ≈ 1.1916
Ok 1st for the triangles you multiply the base X height then multiply by two. For EX: 5x10=50/2=25 so that's the answer for your first triangle.