True coordinates of the vertices of triangle 1 are A(6,6),B(12,9),C(9,6).rotate triangle 1,90 degrees counterclockwise
we have that
the rule of rotate triangle 90 degrees counterclockwise is equal to
(x,y) -------> (-y,x)
so
A(6,6) -------> A'(-6,6)
B(12,9) ----> B'(-9,12)
C(9,6) -----> C'(-6,9)
see the attached figure to better understand the problem
(give me a minute to draw the figure)
Problem N 2
we have
it is translating tree units to the right and 5 units down
the rule is
(x,y) ------> (x+3,y-5)
so
A(6,6) ------->A'(6+3,6-5)
A'(9,1)
B(12,9) ---->B'(12+3,9-5)
B'(15,4)
C(9,6) ----->C'(9+3,6-5)
C'(12,1)