# Trigonometric sprint!!can u come first??

**Calculus**Level 3

Challenge:Do the problem within 20 seconds using your common sense. arccos x means inverse cosine of x defined within [-1,1] Consider the equation

arccos x + arccos y + arccos z = 3(pi)

Hence find the value of

9(xy + yz + zx) ???

Once done post how much time did it take you honestly. YOUR TIME STARTS NOW!!!HURRY