9 pencils cost $7.74 Which equation would help determine the cost of 6 pencils?
Choose 1
1
9
$7.74
9
$7.74
6
C
9
6
$7.74
6
$7.74
9
HI
E
None of the above

Which sum or difference identity would you use to verify that cos (180° - q) = -cos q? a.) sin (a -b) = sin a cos b – cos a sin b b.) cos (a -b) = cos a cos b – sin a sin b c.) cos (a -b) = cos a cosb + sin a sin b d.) sin (a + b) = sin a cos b + cos a sin b