Answer:
The error are
1) The use of the angle addition postulate, for
2) The assumption that
= 90°
The vertical angle property between
and
should be used to find 'x'
x = 5
Explanation:
From the drawing of the circle, we are given;
AD = A diameter of the circle
∴
= 180°
By angle addition postulate, we have;
=
+
+
By substitution property of equality, we have;
180° =
+
+
= 5·x°
= Not given
= 15·x°
However;
is the vertically opposite angle to
∴
=
= (16·x - 5)°
= 15·x° = (16·x - 5)°
15·x° = (16·x - 5)°
∴ 5 = 16·x° - 15·x° = x
x = 5
= 180° - (
+
) = 180° - (15·x° + 5·x°) = 180° - (20·x°)
= 180 - (20×5)° = 80°
= 80°
The error are the use of the angle addition postulate, for
, and the assumption that
= 90° rather than the vertical angle property between
and
in trying to find 'x', from which x = 5.