An angle in a triangle - Math Central

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Question from Morgan, a student:

                 t
        8 t    t 8
        t    78   t
      t               t
  t                      t
t   x                       t
ttttttttttttttttttttttttt
              10

I'm having trouble solving for x I'm not sure where to start ( the ones in the middle of the triangle are both degrees) thanks in advance for your help i really do appreciate it

Hi Morgan.

I hope I have this correct. You have a triangle with base of length 10 units, the other two sides have length 8 units each, the angle at the apex measures 78 degrees and you want the measure of one of the two remaining angles.

Since two sides have the same length this is an isosceles triangle. What does this tell you about the two unknown angles? What do you know about the sum of the three angles in a triangle?

Can you solve the problem now? Write back if you need more help,
Penny

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