Trigonometric area formula: area = 1/2 ab sin(c) what is the area of triangle def? round to the nearest tenth of a square unit. 10.3 square units 18.0 square units 20.0 square units 20.6 square units

1.  10.3 square units.

Step-by-step explanation:  

The general formula for area of triangle is . We can also find area of a triangle using trigonometric area formula.

, where a represents length of base and height of triangle is represented by .  

We have been given two angle measures but we can only use sine of included angle whose two side lengths are given. In our triangle the angle that measures 31 degrees in included angle of sides EF and DF.  

Now let us substitute our given values in the above formula.  

Therefore, the area of triangle DEF is 10.3 square units and 1st option is the correct choice.

answer:

1.14285714286

step-by-step explanation:

divide 40 into 35 and you will get your answer