In a nuclear power plant, water is: used to cool down uranium pellets
used to turn turbines
heated and changed into steam
cooled and changed into ice

Explanation:

in a nuclear power plant water is heated and changed into steam

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°

i really really really really really really dont know