On the solution of sharp angle trigonometric function~ 1. In RT triangle ABC, if angle c = 90 degrees, a + C = 4, cos = 3 / 5, then a =, B =, C = area of triangle ABC? 2. There are two boats on the sea. Boat a is due south of boat B. boat a sails 60 degrees north by east at the speed of 8 knots. Boat B sails 5 knots due east, 3. In RT triangle ABC, angle c = 90 degrees, D is a point on the edge of BC, De is perpendicular to point E, angle ADC = 45 degrees, if de ratio AE = 1:5, be = 3, calculate the area of triangle abd 4. In order to alleviate the parking problem, an underground garage is planned to be built in a certain unit, and the architectural designer has provided the design schematic diagram of the underground garage. According to the regulations, the height limit sign should be posted above the broken road of underground parking, so as to inform the parking people whether the vehicle can be safely used (AB = 9 meters, BC = 0.5 meters) to indicate the height limit, please calculate according to the figure (the figure can't be uploaded, please draw it yourself)

On the solution of sharp angle trigonometric function~ 1. In RT triangle ABC, if angle c = 90 degrees, a + C = 4, cos = 3 / 5, then a =, B =, C = area of triangle ABC? 2. There are two boats on the sea. Boat a is due south of boat B. boat a sails 60 degrees north by east at the speed of 8 knots. Boat B sails 5 knots due east, 3. In RT triangle ABC, angle c = 90 degrees, D is a point on the edge of BC, De is perpendicular to point E, angle ADC = 45 degrees, if de ratio AE = 1:5, be = 3, calculate the area of triangle abd 4. In order to alleviate the parking problem, an underground garage is planned to be built in a certain unit, and the architectural designer has provided the design schematic diagram of the underground garage. According to the regulations, the height limit sign should be posted above the broken road of underground parking, so as to inform the parking people whether the vehicle can be safely used (AB = 9 meters, BC = 0.5 meters) to indicate the height limit, please calculate according to the figure (the figure can't be uploaded, please draw it yourself)

1.a=3/2 c=5/2 b=4 s=3