Which of the following expressions represents "twelve diminished by six times a number"?
1 answer:
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Answer:
70°
Step-by-step explanation:
The total angle in a triangle is 180°. The total angle in a straight line is 180°. From the image attached, the ∠DCA must be greater than 45° because ∠BCA is greater than 90°. This means that ∠DCA is not 36° or 38° or 40° but it is 70°.
Therefore ∠DCA = 70°.
∠BCA + ∠DCA = 180° (angle on a straight line)
∠BCA = 180 - ∠DCA = 180 - 70 = 110°
∠BCA + ∠BAC + 40 = 180° (angle in a triangle)
∠BAC = 180 - 110 - 40 = 30°
