Let ABCD Be a Parallelogram Such That AB = q, AD = p and ∠BAD Is an Acute Angle. If r Is the Vector That Coincides With the Altitude Directed From Vertex B to Side AD, Then r Is Given By
In parallelogram ABCD with AB=q, AD=p, and acute ∠BAD, find the vector r for the altitude from vertex B to side AD, using vector projection.