Someone please help me! Studying for finals and don’t understand how to complete problems like this! Thank you!

(d).

Step-by-step explanation:

sin² β + cos² β = 1

cos (α + β) = cos α cos β - sin α sin β

cos α = √(1 - ) = 21 / 29

cos β = 12 / 13

sin β = √(1 - ) = 5 / 13

sin α = 20 / 29

cos (α + β) = × - × =

step-by-step explanation:

given that there are two triangles j'k'l' and jkl>

the former is got by dilating the second one.

when drawn on a grid, (graph paper) coordinates of vertices of first triangle is

(6,12)j, (9,6)k and (12,9)l

side jk has length = distance between j and k

=

side j'k'=distance between j' and k'

=

ie j'k'l' has sides 1/3 of that of corresponding sides of jkl.

hence scale factor of 1/3 is used to get j'k'l'from jkl

try soting them out first

step-by-step explanation: