Sign In Sign Up Ask an AI advisor

jonlandis6

jonlandis6

05.02.2021 •

Mathematics

? Help if you know how to do this

? Help if you know how to do this

Solved

Show answers

Ответ:

hardwick744

29.03.2022

x = 2.5

Step-by-step explanation:

Given

AC = 2x - 1

AB = 2x + 1

$BC = 2\sqrt{7$

$\angle A = 60^{\circ}$

Required

Find x

To find x, we make use of cosine formula which states:

a^2 = b^2 + c^2 - 2bcCosA

In this case:

BC^2 = AB^2 + AC^2 - 2*AB*BC*CosA

Substitute values

$(2\sqrt{7})^2 = (2x + 1)^2 + (2x-1)^2 - 2*(2x + 1)*(2x - 1)*Cos(60^{\circ})$

Evaluate all exponents

$4*7 = (4x^2 + 4x + 1)+(4x^2 - 4x + 1) - 2(4x^2 - 1)*cos(60^{\circ})$

Open brackets

$28 = 4x^2 + 4x + 1+4x^2 - 4x + 1 - (8x^2 - 2)*cos(60^{\circ})$

Collect Like Terms

$28 = 4x^2 +4x^2+ 4x - 4x+ 1 + 1 - (8x^2 - 2)*cos(60^{\circ})$

$28 = 8x^2+ 2 - (8x^2 - 2)*cos(60^{\circ})$

Substitute 0.5 for cos(60)

28 = 8x^2+ 2 - (8x^2 - 2)*0.5

Open bracket

28 = 8x^2+ 2 - 4x^2 + 1

Collect Like Terms

8x^2- 4x^2 + 2 + 1 - 28 = 0

4x^2 -25 = 0

Collect Like Terms

4x^2 =25

Divide both sides by 4

$x^2 =\frac{25}{4}$

x^2 =6.25

Take positive square root of both sides

$x = \sqrt{6.25$

x = 2.5

0,0(0 оценок)

Ответ:

Aggie9595

08.02.2021

El gobierno de estados central europeo ha de la policía ‍♀️ se han producido un día de estos de gravedad

0,0(0 оценок)

Ask your question to the AI advisor

Ai-bot is an expert in any field and is the perfect companion for reliable and useful answers and advice on a variety of topics, including science, history, technology, art, sports, health, culture and more.

Ask your question

More tips

S Society and Politics 10 Tips for Boosting Your Self-Esteem...
C Computers and Internet How to Create a Folder on Your iPhone?...
G Goods and services How to sew a ribbon: Tips for beginners...
F Food and Cooking How to Make Mayonnaise at Home? Secrets of Homemade Mayonnaise...
C Computers and Internet Which Phone is Best for Internet Surfing?...
F Food and Cooking Everything You Need to Know About Pasta...
C Computers and Internet How to Choose a Monitor?...
H Horoscopes, Magic, Divination Where Did Tarot Cards Come From?...
S Style and Beauty How to Make Your Lips Fuller? Ideas and Tips for Beautiful Lips...

Answers on questions: Mathematics

M Mathematics Triangle abc is an equilateral triangle with side lengths of 10 inches. what is the length, in inches, of ad?...
S Spanish El lenguaje literal puede ser cambiado?...
B Biology Ba kiểu truyền tín hiệu của tế baò...
E English 100 point giveaway teehee...

S Sport S Society and Politics G Goods and services C Cities and Countries A Animals and plants L Legal consultation W Work and Career C Construction and repair H Health and Medicine D Dating, Love, Relationships H Horoscopes, Magic, Divination S Style and Beauty L Leisure and Entertainment S Science and Technology P Photography and Videography A Art and Culture O Other P Philosophy F Food and Cooking B Business and Finance T Travel and tourism F Family and Home A Auto and Moto

Show more

Full access

It will provide effective and fast learning by providing unlimited access to the knowledge base and receiving answers from experts and an AI advisor.

Subscribe

Ask an AI advisor a question

I want advice

ABOUT US

About us
Terms of use
Copyright
Privacy Policy
Cookie policy
Cookie preferences

HELP

Sign Up
FAQ
Security Center

App

Spanish Geography Health Engineering Arts Social Studies Advanced Placement (AP) German SAT History Computers and Technology Physics Chemistry Biology Law Mathematics World Languages French Business Medicine