Solve the right triangle abc with right angle c if b = 30° and c = 10.

Last choice is correct.

Step-by-step explanation:

Given that ∠C=90°, ∠B=30°, c=10

We know that sum of all angles in a triangle is 180 degree.

∠A+∠B+∠C=180°

∠A+∠30°+∠90°=180°

∠A+∠120°=180°

∠A=60°

Now we can use sin or cos whichever applicable to find missing sides

2b=10

b=5

Similarly

a=8.6602

Hence last choice is correct.

-7/8

step-by-step explanation:

instead of subtracting you add the -6/8 and -1/8