Question 774067
Let the three angles of a triangle be a, b and c.
We are given
(1) a = b
and
(2) c = b + 90
and we know that
(3) a + b + c = 180
Put (1) into (3) and get
(4) b + b + c = 180 or
(5) 2*b + c = 180
Now put (2) into (5) to get
(6) 2*b + b + 90 = 180 or
(7) 3*b = 90 or
(8) b = 30 and from (1) we have
(9) a = 30 and from (2) we have
(10) c = 120
Let's check these values with (3).
Is (30 + 30 + 120 = 180)?
Is (60 + 120 = 180)?
Is (180 = 180)? Yes
Answer: angles a, b and c are 30, 30, and 120 degrees, respectively.