Answers>Maths>A Level>Article

Prove that cos(4x) = 8(cos^4(x))-8(cos^2(x)) + 1

cos(4x) = cos(2(2x)) = 2(cos^2(2x)) - 1 = 2 (cos^2(x) - 1)^2 - 1 = 8(cos^4(x)) - 8(cos^2(x)) + 1

Answered by Harry T. • Maths tutor

6093 Views

See similar Maths A Level tutors

Related Maths A Level answers

All answers ▸

Solve the inequality 􏰂|2x + 1|􏰂 < 3|􏰂x − 2|􏰂.

How do I differentiate something of the form a^x?

The quadratic equation 2x^2 + 8x + 1 = 0 has roots a and b. Write down the value of a + b, a*b and a^2 + b^2.

g(x) = e^(x-1) + x - 6 Show that the equation g(x) = 0 can be written as x = ln(6 - x) + 1, where x<6

Popular Requests

Maths tutor Chemistry tutor Physics tutor Biology tutor English tutor GCSE tutors A level tutors IB tutors Physics & Maths tutors Chemistry & Maths tutors GCSE Maths tutors

CLICK CEOP

Internet Safety

Payment Security

Cyber

Essentials

MyTutor is part of the IXL family of brands:

IXL

Comprehensive K-12 personalized learning

Rosetta Stone

Immersive learning for 25 languages

Wyzant

Trusted tutors for 300 subjects

Education.com

35,000 worksheets, games, and lesson plans

Vocabulary.com

Adaptive learning for English vocabulary

Emmersion

Fast and accurate language certification

Thesaurus.com

Essential reference for synonyms and antonyms

Dictionary.com

Comprehensive resource for word definitions and usage

SpanishDictionary.com

Spanish-English dictionary, translator, and learning resources

FrenchDictionary.com

French-English dictionary, translator, and learning

Ingles.com

Diccionario ingles-espanol, traductor y sitio de apremdizaje

ABCya

Fun educational games for kids