# math

posted by
**bart**
.

ive been working on my sat's and i cant seem to figure out how to answer the following question.

a right angle is given. the length of ba is 20. what is the approx length of bc?

sin= .643

cos= .766

tan= .839

the answer is 12.9 but i don't know how that is.

I assume bc is the other leg, and ba is one leg.

Isnt Sin of the base angle= bc/ba?

then bc= .643*ba