can you solve it all, thank you

Diedre rides her sled down an icy, frictionless hill. When she reaches level ground at the bottom, she is traveling at - vi = 4.0m/s and has a glancing collision with her sledding buddy Brynn, who is initially at rest. Both sledders have the same mass, and they are using identical sleds. The colli- sion causes Diedre's velocity vector to deflect by an angle of - 0 = 21', and the velocity vectors of both sledders are perpen- - dicular to each other after the collision. What is Brynn's speed v2 after the collision? For the limits check, investigate what happens to Brynn's speed v2 as Diedre's initial speed vi - 0