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1. The 2nd angle of a right angle is 30°. Then what is the third angle?/একটি সমকোণী ত্রিভুজের দ্বিতীয় কোণটির মাপ ৩০° হলে তৃতীয় কোণটির মাপ কত?
- A. 80°
- B. 80°
- C. 80°
- D. 80°
Answer: Option C
Explanation:
First,we know that all the angles in a triangle add up to 180 degrees.
Each triangle has 3 angles. Thus, we have the sum of three angles as shown:
180 = A + B + C
where we have angles A, B, and C. In our right triangle, one angle is 30 degree and we'll call that angle A. The other known angle is 90 degrees and we'll call this angle B. Thus, we have
180 = 30 + 90 + C
Simplify and solve for C.
180 = 120 + C
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