First picture answer:
⇒Sum of interior angles of a triangle is 180°,this means that ∠1 +37°+24°=180°
⇒m∠1=119°
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Second picture answer:
⇒An exterior angle of a triangle is created by extending one side of the triangle.
⇒ Exterior angle at this point is m∠1
⇒If a side of a triangle is produced, then the exterior angle so formed is equal to the sum of the two interior opposite angles.
⇒The two interior angles at this point are 76° and 52°
⇒The statement above just means m∠1=76°+52°
m∠1=128°
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Third picture answer:
⇒If a side of a triangle is produced, then the exterior angle so formed is equal to the sum of the two interior opposite angles.
⇒The exterior angle at this point is 104° and the two interior angles are 79° and m∠1
⇒The statement above means that
104°=m∠1 +79°
⇒Let us solve for the unknown angle m∠1
m∠1=104°-79°
m∠1=25°