What is an opportunity cost? a) something absent in a command economy. b) when goods are recycled into other goods. c) when there is not a scarcity of goods and resources. d) the next-best alternative you give up in order to do something else.

angle a = 40.6°

step-by-step explanation:

for any right angle triangle we know the pythagoras theorem reveals

hypotenuse² = height²+base²

by this formula we will calculate the length of hypotenuse

h² = 6²+7²

⇒ h =√36+49 = √85 = 9.22

now from the given triangle sin a = height/ hypotenuse

                                                sin a = 6/9.22 = 0.651

therefore

so angle a = 40.6°