Fishing Craft Technology

Unit 3 - Design procedure

3.2. The trapezoidal rule
A trapezoid is a plane four sided figure having two sides parallel. If the lengths of these sides are Y1 and Y2 and they are h apart, the area of the trapezoid is given by

A curvilinear figure can be divided into number of approximate trapezoids by covering it with ‘n’ equally spaced ordinates ‘h’ apart, the breadths at the ordinates in order being Y1, Y2, Y3 ..................Yn. Commencing with the left hand trapezoid, the areas of each trapezoid are given by

This is termed as TRAPEZOIDAL RULE. The more numerous the ordinates, the most accurate will be the answer. Thus to evaluate the expression of the shape is divided into evenly spaced section ‘h’ apart, the ordinates measured and substituted in the rule given above. If the ordinates represent cross–sectional areas of solid, then the integration gives the volume of that solid.