Answer: Angle X = 30
Step-by-step explanation: First and foremost, we should recognize that an isosceles triangle has two sides equal and the two angles subtended by the two equal sides are also equal in measurement.
This means. In the diagram on the left, line DE = line DF and that is 10cm.
The similar angles are the ones subtended by the lines identified as being equal, that is
Angle E = angle F and that is 75. If both angles measure a combined total of 150 the third angle can be derived simply as
180 - (75+ 75)
{Sum of angles in a triangle = 180}
180 - (150)
= 30
Therefore angle D = 30.
However having been given in the question that both triangles are similar and are isosceles, then
Angle D = Angle X and that is 30
