sin(α/2)= √(( 1-cosα)/2).
cos(α/2)= √(( 1+cosα)/2).
tan(α/2)=√(( 1-cosα)/( 1+cosα))= sinα/( 1+cosα)=( 1-cosα)/sinα.
Extended data:
Half-angle formula is a formula for finding trigonometric functions such as sine, cosine and tangent of an angle (such as ∠A).
How to learn math and geometry well in junior high school?
1. Establish the foundation of mathematical geometry
The first step to learn mathematical geometry well in junior high school is to establish the foundation of mathematical geometry. Students should master basic geometric concepts and theorems, such as lines, angles, triangles, quadrilaterals, etc. Only by establishing these foundations can we better understand the following knowledge points.
2. Understand the essence of geometry knowledge
Students should understand the essence of geometry knowledge, not just rote learning. For example, students should understand the essence that the sum of the internal angles of a triangle is 180 degrees, instead of just remembering this theorem. Only by understanding the essence of geometry knowledge can we better apply this knowledge.
3. Do more geometry problems
Doing more geometry problems can help students deepen their understanding of geometry knowledge. Students should choose a topic with appropriate difficulty to practice, such as starting with a simple right triangle and gradually improving the difficulty.
4. Summarize geometry problem solving methods
Students should sum up the methods to solve geometric problems, such as drawing pictures and using mathematical formulas. Only by mastering the methods to solve geometric problems can we better apply geometric knowledge to solve practical problems.
5. Pay attention to the application of geometry
Students should pay attention to the application of geometry, such as applying geometry knowledge to solve problems in daily life. For example, calculate the discounted price when shopping, or measure the area of the room when decorating. Only by applying geometry knowledge to real life can we better understand and master this knowledge.