Calculate unknown angles and give explanationsusing the following geometrical properties of circles:• angle in a semicircle = 90°• angle between tangent and radius = 90°.

Sure, I can help with that. However, I need more specific information about the problem you're trying to solve. Are you trying to find the angle in a specific circle or triangle? If so, could you please provide more details about the figure?

Here's a general explanation of how you might use these properties:

1. Angle in a semicircle = 90°: This property tells us that any angle formed at the circumference of a circle by a diameter and a chord is always 90 degrees. So, if you know that one side of your angle is a diameter, then you know the angle is 90 degrees.

2. Angle between tangent and radius = 90°: This property tells us that any angle formed between a tangent line to a circle and the radius of the circle that intersects the tangent line at the point of tangency is always 90 degrees. So, if you have a tangent line and a radius that intersect, you know the angle between them is 90 degrees.

These properties can be used to solve for unknown angles in a variety of geometric problems involving circles. However, without more specific information about your problem, I can't provide a more detailed solution.