Help me out please???

What is sin 7x/4 ? i need on this urgent trig

Given: pqrs is a parallelogram prove: pr and qs bisect each other at t

Consider a cube that has sides of length l. now consider putting the largest sphere you can inside this cube without any point on the sphere lying outside of the cube. the volume ratio -volume of the sphere/ volume of the cube is 1. 5.2 × 10−1 2. 3.8 × 10−1 3. 1.9 4. 2.5 × 10−1 5. 3.8