The gangway and the platform form a triangle with the ground:
So, we need to find the value of x (distance, in meters, of the bottom of the gangway from the base of the platform).
Since that is a right triangle, we can find x using the formula:
1.3² + x² = 3.2²
1.3² + x² - 1.3² = 3.2² - 1.3²
x² = 10.24 - 1.69
x² = 8.55
√x² = √8.55
x ≅ 2.92
Therefore, the bottom of the gangway is approximately 2.92 m far from the base of the platform.