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Edexcel A-level Maths Double angle formulas

Double angle formulas

This page covers the following topics:

1. Double angle formula for sine
2. Double angle formula for cosine
3. Double angle formula for tangent
4. Problems with double angle formulas

The sine double angle formula involves trigonometric functions of double angles, i.e sin2A.

Double angle formula for sine

The cosine double angle formula involves trigonometric functions of double angles, i.e cos2A.

Double angle formula for cosine

The tangent double angle formula involves trigonometric functions of double angles, i.e tan2A.

Double angle formula for tangent

The sum of two trigonometric functions can be expressed as a single trigonometric function in the form Rcos(xΒ±Ξ±) or Rsin(xΒ±Ξ±).

Problems with double angle formulas

1

Give the addition formula for sin(A + B).

Give the addition formula for sin(A + B).

2

Express cos60Β° by using the functions of 30Β°.

Express cos60Β° by using the functions of 30Β°.

3

Rsin(x βˆ’ Ξ±) is a way of expression what general equation?

Rsin(x βˆ’ Ξ±) is a way of expression what general equation?

4

Rearrange the equation cos2A = cosΒ²A βˆ’ sinΒ²A to give an expression for sine of half the angle, sin(B/2), given that 2A = B.

Rearrange the equation cos2A = cosΒ²A βˆ’ sinΒ²A to give an expression for sine of half the angle, sin(B/2), given that 2A = B.

5

Express Rcos(x βˆ’ Ξ±) in terms of sine and cosine functions with an argument x and positive coefficients A and B.

Express Rcos(x βˆ’ Ξ±) in terms of sine and cosine functions with an argument x and positive coefficients A and B.

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