In the "old city reconstruction" of a city, it is planned to plant turf on a triangular open space in the city as shown in the figure to beautify the environment Planting turf to beautify the environment is known to cost 80 yuan per square meter. How much does it cost to buy this kind of turf?

Extend CA line, take BD perpendicular to Ca at D,

It is planned to plant turf on a △ ABC open space to beautify the environment. It is known that ∠ a = 150 ° turf costs a yuan per square meter, and it will take at least a few years to buy this kind of turf
The ABC is an obtuse triangle, AB 20m, AC 30m, a = 150 degree

Make CD ⊥ AB and intersect the extension of BA at point D
∵∠BAC=150°
∴∠CAD=30°
∵AC=30
∴CD=15
∴S△ABC=1/2*20*15=150
150*a=150a
It costs 150 yuan