Applied problems of plane vector in Senior High School A sailboat set sail from place a to place B. at that time, there was only wind blowing from west to north. The wind speed was 15 knots and 2 nautical miles per hour. If the sailboat intended to reach its destination within 5 hours, what direction and speed should it sail B is due east of a, 200 nautical miles Accurate to 1 degree, 0.1 nautical miles

Applied problems of plane vector in Senior High School A sailboat set sail from place a to place B. at that time, there was only wind blowing from west to north. The wind speed was 15 knots and 2 nautical miles per hour. If the sailboat intended to reach its destination within 5 hours, what direction and speed should it sail B is due east of a, 200 nautical miles Accurate to 1 degree, 0.1 nautical miles

In the picture, it represents the relationship of three displacement vectors. Determine the size of the unknown vector according to the trigonometric function relationship. This is the displacement of 5 hours, and then divide it by time to calculate the speed. Direction is the direction of the unknown vector in the picture, and determine its size according to the trigonometric relationship

In RT △ ABC, angle c = 90 °, ab = 5, AC = 4, find the value of vector ab · vector BC

According to Pythagorean theorem | ab | = 5 | BC | = 3 | AC | = 4, then ab · BC = 3 × 5 × (- 3 / 5) = - 9