Need some clarification about a triangle with three inner triangles that are isosceles
|dw:1354214968597:dw|
In an isosceles triangles, the base angles are congruent. The sum of the measures of the angles of a triangle is 180. Also, the angles in the middle are 140, 120 and one more. They go around a full circle, so the total is 360 degrees, and you already know 140 and 120.
then would you minus 100 from the other angles to find abc,bca, and cab?
For angle BOA, 360 - 140 - 120 = 100
Now look at triangle ABO. One angle measures 100, the other two angles are congruent and measure x. x + x + 100 = 180
x is the measure of angles ABO and BAO
in my text book its gives an example then the solution i just dont get how they got one part of the solution: (angle)coa =120, then (angle)oca + (angle)oac = 30
Look at the triangle COA. You stated that it is isosceles. In an isosceles triangle, the angles opposite the congruent sides are congruent.
That means that is triangle COA, angles OCA and OAC are congruent and measure the same. You also know that the sum of the measures of all angles of a triangle is 180. Call the measure of angle OCA "y". Then the measure of angle OAC is also "y" because OCA and OAC are congruent. you then have y + y + 120 = 180. SOlve that and you get y = 30
first find angle AOB 120+140 +<AOB=360 so <AOB=100 now for each inner triangle find the other two angles. For example for triangle AOC, <cao+<aco+<aoc=180 Fill in the known angle. So <cao+<aoc+120=180 <cao+<aoc=180-120=60 since <cao=<aoc <cao=30=<aoc Now do the same for the other 2 triangles also. Once all angles are marked, you will add the relevant angles. In the end you will get <abc=40+20=60 <bca=20+30=50 <cab=30+40=70
Join our real-time social learning platform and learn together with your friends!