evonleong0203
evonleong0203 evonleong0203
  • 13-06-2020
  • Mathematics
contestada

Prove
that
2 cos (A +45°) cos (B-45°) = cos 2A​

Respuesta :

surjithayer10 surjithayer10
  • 13-06-2020

Answer:

Step-by-step explanation:

2 cos(A+45)cos (B-45)

=2[cos A cos 45-sin A sin 45][cos B cos 45+sin B sin 45]

=2[cos A ×1/√2-sin A ×1/√2][cos B×1/√2+sin B×1/√2]

=2[1/√2(cos A-sin A)][1/√2(cos B-sin B]

=2×1/√2×1/√2 (cos A-sin A)(cos B+sin B)

=cosA cos B+cos A sin B-sin A cos B-sin A sin B

=cos A cos B-sin A sin B-(sin A cos B-cos A sin B)

=cos (A+B)-sin (A-B)

i think there should be A in place of B.

then

=cos (A+A)-sin (A-A)

=cos 2A-sin 0

=cos 2A

as sin 0=0

Answer Link

Otras preguntas

How do you change a ratio into a fraction baseballs to basketballs
in a given amount of time, James drove twice as far as Rachel. Altogether they drove 120 miles. Write an equation to help find the number of miles driven by eac
A focus on how we encode, process, store, and retrieve information is most relevant to the
You have a chocolate bars and you ate 1/4 how much chocolate bars will you have
What is 1000mm=. m What is 65mm=. m What is4.92m=. m What is 3mm=. m
Segment lm is the midsegment of trapezoid abcd. ab = 58, and dc = 98. what is lm?
The relationship between ozone in the stratosphere and the presence of cfcs?
What are 5 things that houdini did that helped him develop into a escape artist?
Three norms that are lagging
What area is sacred to all three major monotheistic religions, and why is it important to each?