1. B

    Triangle in a cyrcle

    Does anyone know how to solve this? It has no information, just the answer is given, which is 72deg.
  2. TriKri

    Finding the angle and axis lengths of an ellipse

    Hi, I have an ellipse defined by \|\mathbf{A}^{-1}v\| = 1, where v is a vector in the ellipse and \mathbf A is a real, invertible 2-by-2 matrix. How can I find the lengths of the axis of the ellipse as well as the angle of the major axis? I need to know this because I want to plot the ellipse...
  3. R

    Find the angle ADB

    Can any one help me finding the angle ADB if ACB = 30, CD = DB ?
  4. L

    formula for the angle between two intersectiing planes

    Hello, Referring to the picture below, I have 4 points in orthogonal 3D space (sorry if I couldn't make the picture look more 3d). The vectors AB and BC lie in an Euclidian plane while the vectors AB and BD lie in a different Euclidian plane. These planes intersect along the vector AB. I am...
  5. H

    How can measure of a minor arc is equal to measure of its central angle in a circle?

    How can measure of a minor arc is equal to measure of its central angle in a circle?
  6. R

    Find the angle

    Can anyone help me finding the angle ADB ?
  7. L

    find the angle between two lines formed by three points in n-space

    Hello, I wasn't sure where to post this, so please feel free to move it. In some ways, I suspect this is a very elementary question for an expert, so I posted in on the pre-university side. Here is an example in 2D of the problem I am looking at, given three sets of coordinates...
  8. M

    Find the angle X

    Hi Please Help me to find the angle X with reasons.(Diagram attached) BD & CD points are on BE side of the ▲ABE. AC=DE. Find the value of angle X
  9. X

    angle outside triangle

    this is actually mohr's circle formula, forget about the theory,let's focus on the mathematics part. I couldnt understand why the tan( 2 θs1) = -(σx -σy) / 2τxy ? 2θs1 is outside the triangle theorically, tan(180-α )= -tan( α ) , so tan( 2 θs1) = -(σx -σy) / 2τxy , the vertical staright line of...
  10. X

    limit of angle

    can someone explain about the limit of ∅ is taken from 0 to pi only?
  11. X

    Triangle with Angle,Side,Ratio known

    Hello everybody, I've got a triangle with 1 angle, 1 side and the ratio of the other 2 sides known. But no matter what I do, I keep running in circles. Is there a way to leave the unknown "d" alone in one side of the equation?
  12. C

    Trig angle Formulas

    Hey, I am confused as to how to break down this question. "Evaluate using formulas developed in this section." a) sin 11pi/12 the formulas are the addition and subtraction as well as double angle formulas. i know that 11pi/12 = pi/3 + pi/4 + pi/4 + pi/6 but am not sure how to turn it into a...
  13. R

    If (a,b) is a point on the terminal side of angle t in standard position, then cos(t)

    How do I know what it is supposed to be? Please explain. Thank you!
  14. N

    long question , confusing , please check them for me,urgent!!!

    Same as the title, please figure out what is wrong for my working ,, questions: 1)A helicopter takes off from a point 120m away from an abserver located on the ground, and rises vertically at a constant rate of 2.5m/s.At what rate is the elvation angle of the observer's ine of sight to te...
  15. M

    Find radian measure of a centralized angle

    Circle radius is 1cm. Area of certain sector is pi/5cm^2 What is the radian measure of the central angle. Do I do C= 2pi(1) then 2pi*5cm^2?
  16. S

    Parallelogram Help?

    A parallelogram exists within a rectangle which measures 15 inches tall by 20.5 inches wide. A=15 inches B=20.5 inches C=1.5 inches (C makes a 90° angle with X) Solve for lengths X and Y and angle Z of the parallelogram and please tell me how you did it!
  17. G

    Help calculating a point in 2d space on a rotating right angle triangle

    I am trying to solve for a point on a triangle that rotates around a fixed point. For ease of calculation this point is at X: 0 Y: 0 The length and width of the triangle are always fixed, the only thing that changes is the rotation angle. How can I solve for X: ??? and Y: ??? taking into...
  18. J

    Proving angle equivalency

    Hi everyone, Is there a way to prove that angle B and angle C are equivalent in this situation? The argument my textbook made certainly seemed to imply that, and it really bothers me that I can't quite see it. I'm worried it's really simple and I'm overthinking it... I haven't taken geometry in...
  19. B

    find an angle

    Hi! I have a trig problem. I need to find the angle EAB. All known sides and angles you can find on the sketch right here: Any help greatly appreciated.
  20. Jason76

    Two Different Angle Vector Formulas ?

    Formula to find the angle between vectors: |a|\,\,|b| = \cos\theta or \cos\theta = \dfrac{a\,\,*\,\,b}{|a|\,\,|b|} where a and b are vectors When should we use one formula rather than the other?