how to offset vector 3 by an angle unity

 //Setting up Vector3's for rays Vector3 rayPosition = new Vector3(transform.position.x, headHeight, transform.position.z); Vector3 leftRayRotation = Quaternion.AngleAxis(-fovAngle, transform.up) * transform.forward; Vector3 rightRayRotation = Quaternion.AngleAxis(fovAngle, transform.up) * transform.forward;  //Constructing rays Ray rayCenter = new Ray(rayPosition, transform.forward); Ray rayLeft = new Ray(rayPosition, leftRayRotation); Ray rayRight = new Ray(rayPosition, rightRayRotation);  //(Doing things with rays...)

 Vector3 noAngle = spawn.forward; Quaternion spreadAngle = Quaternion.AngleAxis(-15, new Vector3(0, 1, 0)); Vector3 newVector = spreadAngle * noAngle;  Ray ray = new Ray (spawn.position, newVector);  CastProjectiles(shotDistance, ray);