If the angle formed by two radii of a circle is $100°$ , the angle between the tangents at the ends of those radii is ____.

Here, two radii and corresponding tangents at the ends of those radii form a quadrilateral.

Tangents are at a right angle to the radius.

As we know that the sum of all angles in a quadrilateral is 360⁰.

x + 90+100+90 = 360⁰

x + 280 = 360⁰

x = 360⁰ - 280⁰ 

x = 80⁰

Hence, the angle between the tangents at the ends of those radii is 80⁰.