6cm, 15cm, 6cm does it make a triangle

The line y = x + passes through (−3, 7) and is parallel to y = 4x − 1.

Awall map has a scale of 128 miles = 6 inches. the distance between springfield and lakeview is 2 feet on the map. what is the actual distance between springfield and lakeview? 384 miles 512 miles 1.13 miles 42.7 miles

Me, the vertices of quadrilateral coat are c(2,0), o(7,0), a(7,2) and t(2,2). prove that coat is a rectangle.