PLEASE HELP
Which sum or difference identity could be used to prove that sin(π + q) = -sin q is an identity?
A: cosπcosq - sinπsinq
B: cosπcosq + sinπsinq
C: sinπcosq - cosπsinq
D: sinπcosq + cosπsinq

Jonathan pays $1.90 per pound for potatoes. he buys 8.3 pounds of potatoes. he determines that he will pay $15.77, before tax, for the potatoes. which best describes the reasonableness of jonathan’s solution? jonathan’s answer is reasonable because there are two decimal places in the factors and two in the product. jonathan’s answer is unreasonable because there are three decimal places in the factors and two in the product. jonathan’s answer is reasonable because is 16, and 16 is close to 15.77. jonathan’s answer is unreasonable because is 8, and 8 is not very close to 15.77.

Does the problem involve permutations or? combinations? do not solve. the matching section of an exam has 4 questions and 7 possible answers. in how many different ways can a student answer the 4 ? questions, if none of the answer choices can be? repeated?

Write the expression as a constant , a single trigonometric function, or a power of a trigonometric function. sin x cos x/ tan x