tolong dikerjain serta caranya

Trigonometri
A lancip danB tumpul

tan A = 12/5 = y/x
x= 5, y =12 -->  r = 13 (pitagoras)
sin A = y/r= 12/13
cos A = x/r = 5/13

sin B = 4/5 = y/r
y = 4, r = 5, --> x = 3 (pitagoras)
cos B = - x/r = - 3/5
tanB = - y/x = -4/3

a. sin (A+B) = sin A cos B + cos Asin B = (12/13)(-3/5) + (5/13)(4/5)
= -36/65 + 20/65
= - 16/25

b. Cos (A+B)= cos A cos B - sin A sin B = (5/13)(-3/5) - (12/13)(4/5)
= - 15/65 - 48/65
= - 63/65

c. tan (A-B) = (tan A - tan B)/ ( 1 + tan A. tan B)
= (12/5 - (-4/3)) / ( 1 + 12/5 x - 4/3)
= (12/5 + 4/3) / ( 1 - 48/15)  kalikan 15/15
= (36 + 20) /(15 - 48)
= 56/-33
= - 56/33