Please help me asap!!

Step-by-step explanation:

sin a = 4/5 then cos a = 3/5

sin b = 12/13 then cos b = -5/13 (because in quadrant 2)

then

cos (a+b) = cos a cos b - sin a sin b

cos (a+b) = 3/5 * (-5/13) - 4/5 * 12/13

cos (a+b) = -3/13 - 48/65

cos (a+b) = -15/65 - 48/65

cos (a+b) = - 63/65

cos (a+b) = -63/65

in decimal -0.969 ≈ -0,97

square root

step-by-step explanation:

6mm^3 or .6cm^3

      216

      /   \

  36     6

  /   \     /

6     6   6

factor trees are nice.