Why are reservoirs constructed with broad dams?

Tracy solved the following problem. which of the statements is true? 9 ÷ 3 + 6 × 2 3 + 6 × 2 9 × 2 18 her answer is correct. her answer is incorrect. she should have multiplied before dividing. her answer is incorrect. she should have multiplied before adding. her answer is incorrect. she should have added before dividing.

Which of the following is the shape of a cross section of the figure shown below

Write the sine and cosine values of a, b, respectively, in the figure for (1) and (2) + explanation.