Answer:
Step-by-step explanation:
well if you see clously, you can see that there are actually 3 right triangles
the bigger(yellow color) and the smaller one(blue color), and the medium (right side to the smaller one)
the bigger triangle( yellow) has a 90 degrees angle
which we can subtract 27 from 90
but from where 27? well it's from the smaller triangle
so 90 - 27 = 63
the big angle is 63, but we're not finished yet!
let's make an equation:
63 = (2a+9)
subtract 9 from both sides
63 = (2a+9)
-9 -9
54 = 2a
27 = a
and we're done!
if you still in doubt
let's check it out
in the big triangle:
a + 27 + (2a + 9) + x (angle that we don't know yet) = 180 ( all triangles is 180 degrees if you don't know)
let's subtitute the value "a"
27 + 27 + (54 + 9 ) + x = 180
54 + 63 +x = 180
117 + x = 180
subtract 117 from both sides
117 + x = 180
-117 -117
x = 63
let's subtitute to the small triangle
63 + 27 + 90 = 180
so yeah, we tried to find the small triangle and it worked, this proves that a = 27 !
hope this helps !
