The vectors a=i+3j\mathbf a=\mathbf i+3\mathbf ja=i+3j and d=5i+kj\mathbf d=5\mathbf i+k\mathbf jd=5i+kj satisfy ∣d−a∣=25|\mathbf d-\mathbf a|=2\sqrt5∣d−a∣=25. Find kkk.