First you will subtract right to left and then what ur left with is the sum.
Answer:
d. 690.1 units²
Step-by-step explanation:
1. You can use the Heron's formula to calculate the area of the triangle, which is:

Where:

2. Calculate
:

3. Substitute values into the formula shown above and calculate the area, as following:

4. Therefore, the area is 690.1 units².
The second part = 1
the second part could be written sin²x.(1/sin²x), since cscx =1/sinx
hence 1 = 1