Math Help - find theta

find theta without the use of the law of cosines

see image attached

Originally Posted by calc123

find theta without the use of the law of cosines

see image attached

Why can't you use the Cosine Rule?

well my prof told me i didnt need to know that for the test. so im trying to solve it a diff way

Hello, calc123!

Find without the use of the Law of Cosines.

Code:

      |     x     A
    D + - - - - - o
      |         **
      |     5 * *
    y |     *  *
      | θ *   *
      | *    *
    B o     * 7
      |    *
      |   *
    3 |  *
      | *
      |*
    C o

We have: .

Let: .




Subtract [2] - [1]: .

Hence: .


Therefore: .