AonZ
  • AonZ
Yr11 3unit question help pls! ABC is a triangle and D is the midpoint of AC. BD=m and angle ADB = theta (a) show that cos(theta) = 4m^2 + b^2 - 4c^2 / 4mb and write an expression for cos(180-theta). (b) show a^2 +c^2 = 2m^2 + 1/2 b^2 I have done part (a) and need help on part (b) pls.
Mathematics
schrodinger
  • schrodinger
See more answers at brainly.com
At vero eos et accusamus et iusto odio dignissimos ducimus qui blanditiis praesentium voluptatum deleniti atque corrupti quos dolores et quas molestias excepturi sint occaecati cupiditate non provident, similique sunt in culpa qui officia deserunt mollitia animi, id est laborum et dolorum fuga. Et harum quidem rerum facilis est et expedita distinctio. Nam libero tempore, cum soluta nobis est eligendi optio cumque nihil impedit quo minus id quod maxime placeat facere possimus, omnis voluptas assumenda est, omnis dolor repellendus. Itaque earum rerum hic tenetur a sapiente delectus, ut aut reiciendis voluptatibus maiores alias consequatur aut perferendis doloribus asperiores repellat.

Get this expert

answer on brainly

SEE EXPERT ANSWER

Get your free account and access expert answers to this
and thousands of other questions

AonZ
  • AonZ
|dw:1367620733749:dw|
AonZ
  • AonZ
@jim_thompson5910 @Mertsj help pls
AonZ
  • AonZ
umm im pretty sure ADC is 180. Why wouldnt it be?

Looking for something else?

Not the answer you are looking for? Search for more explanations.

More answers

Loser66
  • Loser66
since I saw (theta) symbol at ADB and you indicate about ADC is theta
AonZ
  • AonZ
im sorry ADB is theta :P
Loser66
  • Loser66
ok, let tag someone who is good at geometry and trig @Mertsj
Mertsj
  • Mertsj
|dw:1367623308982:dw|
AonZ
  • AonZ
hmm yes i proved part a but i couldnt get part b. I think you need to do something with part a to get part b
Mertsj
  • Mertsj
\[c^2=m^2+(\frac{b}{2})^2-2m(\frac{b}{2})\cos \theta \]
Mertsj
  • Mertsj
Solve for cos theta
AonZ
  • AonZ
ok yea i proved that part
AonZ
  • AonZ
and cos(180-theta) is putting a negative sign infront of that equation
AonZ
  • AonZ
how can we prove part b though?
Mertsj
  • Mertsj
From the first part you have an expression for cos (180-theta) Get another expression for cos (180-theta) using triangle BCD Equate those two expressions for cos(180-theta) and solve for a^2+b^2
AonZ
  • AonZ
- 4m^2 + b^2 - 4c^2 / 4mb = 4m^2 + b^2 - 4a^2 / 4mb right?
AonZ
  • AonZ
ok i solved it thank you

Looking for something else?

Not the answer you are looking for? Search for more explanations.