Question

Find the exact value of sin82.5

Answer 1

Express the above as 90 - x first

Answer 2

Apply the half-angle formula twice

Answer 3

\[\sin(90-x) = \cos x\]
\[\cos (\frac{x}{2}) = \sqrt{\frac{\cos x +1}{2}}\]

Answer 4

is it 7.5 degrees?

Answer 5

90-82.5?

Answer 6

yes

Answer 7

0.73018385915316689224111517182195006273281159789180934210

Answer 8

to be exact....

Answer 9

then 30/2 = 15 and 15/2 = 7.5

Answer 10

@RICARDOismyfirstname , that is a decimal approximation :)
you cant express irrational number exactly with deciamals

Answer 11

cos\[\cos(7.5\div2)=\sqrt{cosx+1}\]

Answer 12

Yeah, man you're right