1, sum formula of two angles:

sin(A+B)= Sina cosb+cosa sinb sin(A-B)= Sina cosb-sinb cosa

cos(A+B)= cosa cosb-Sina sinb cos(A-B)= cosa cosb+Sina sinb

tan(A+B)=(tanA+tanB)/( 1-tanA tanB)tan(A-B)=(tanA-tanB)/( 1+tanA tanB)

ctg(A+B)=(ctgActgB- 1)/(ctg B+ctgA)ctg(A-B)=(ctgActgB+ 1)/(ctg B-ctgA)

2. Double angle formula:

tan2A = 2 tana/( 1-tan2A)ctg2A =(ctg2A- 1)/2c TGA

cos2a = cos2a-sin2a = 2 cos2a- 1 = 1-2 sin2a

3. Half-angle formula:

sin(A/2)=√(( 1-cosA)/2)sin(A/2)=-√(( 1-cosA)/2)

cos(A/2)=√(( 1+cosA)/2)cos(A/2)=-√(( 1+cosA)/2)

tan(A/2)=√(( 1-cosA)/(( 1+cosA))tan(A/2)=-√(( 1-cosA)/(( 1+cosA))

ctg(A/2)=√(( 1+cosA)/(( 1-cosA))ctg(A/2)=-√(( 1+cosA)/(( 1-cosA))

Mathematics learning methods in senior one.

Grasp the textbook to understand. Improve math ability, of course, through the classroom. We should make full use of the classroom. The process of mathematics learning in senior one is alive, so is the object of teachers' teaching, which changes with the development of teaching process, especially when teachers pay attention to ability teaching, the teaching materials can't be reflected.

Mathematical ability is formed simultaneously with the occurrence of knowledge. Whether forming a concept, mastering a law or doing an exercise, we should cultivate and improve it from different ability angles. Through the teacher's teaching in the classroom, we can understand the position of what we have learned in the textbook and the relationship with the previous knowledge. Only by mastering the teaching materials can we master the initiative in learning.