Test points: This question tests the properties of rectangles, the judgment and properties of congruent triangles, the judgment and properties of similar triangles, and the judgment of parallelograms. Important and difficult points: Master the properties of squares and the judgme

Test points: This question examines the properties of rectangles, the judgment and properties of congruent triangles , the judgment and properties of similar triangles , and the judgment of parallelograms .

key points: master the properties of squares and the judgment of parallelograms, construct similar triangles of congruent triangles by making auxiliary lines, and answer questions based on known information.

This question is a comprehensive geometry question. It examines the tangent properties of circles, properties of similar triangles, trigonometric functions solution to right triangles, Pythagorean theorem , arc length calculation, etc. It is highly comprehensive and students should be flexible when solving the problem. Solve problems with the mathematical knowledge you have learned.

This question is a comprehensive question on similar triangles. It examines the determination of similar triangles, the Pythagorean theorem, the properties of right triangles, acute angle trigonometric functions and other knowledge. Adding appropriate auxiliary lines to construct similar triangles or congruent triangles is the key to this question.

This question is a comprehensive question on quadrilaterals. It examines the properties of rhombuses, the determination and properties of congruent triangles, the properties of isosceles triangles, and the properties of right triangles. Mastering the properties of rhombuses and proving that triangles are congruent is the key to solving the problem.