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Answer:
#5
Area = Area of bigger triangle - Area of small triangle

#8
Area = area of square + area of two right angled triangles

Answer:
Step-by-step explanation:
Sum of all three angle in a triangle=180
Given angles are 35°,45°
Let the remaining angle =x
So 35 +45+X=180
X=180-80
X=100°
Remaining angle =X=100° is the answer