This video lecture from Geometry (F.Sc. second year Mathematics) covers: Question numbers 11-13 of exercise 3.3. In these questions we find the value of unknown element of determinant, identify singular and non-singular matrices, find the inverse of 3x3 matrices. Find more e-learning material and educational video lectures in Urdu at maktab.pk. These videos are free to use for promotional and commercial purpose by keeping the credits to Maktab.