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The length of the base of a triangle is equal to the perimeter of a square whose diagonal is 72 cm and the corresponding height of the triangle is equal to the length of a side of the square whose area is 169 sq cm. The area (in sq cm) of the triangle is:
152
182
156
130
182
Find side of first square using diagonal (d=s2) to get perimeter (base = 4s), then find side of second square from its area (169=13) to get height, and compute area as 21×Base×Height.
Diagonal of the square = 72 cm; Area of the second square = 169 sq cm
Area of Triangle=21×Base×Height
Find side of first square using diagonal (d=s2) to get perimeter (base = 4s), then find side of second square from its area (169=13) to get height, and compute area as 21×Base×Height.
Confusing the perimeter of the first square with its side length or incorrectly calculating the square root of 169 as 14 instead of 13.
Step 1: Find the side and perimeter of the first square
The diagonal of the first square is given as 72 cm. The diagonal of a square of side s is s2. Thus, the side s1=7 cm. The perimeter of this square is 4×7=28 cm. Therefore, the base of the triangle is 28 cm.
Base=4×7=28 cm
Step 2: Find the side of the second square
The area of the second square is given as 169 sq cm. The side s2 of the square is the square root of its area: s2=169=13 cm. Therefore, the height of the triangle is 13 cm.
Height=169=13 cm
Step 3: Calculate the area of the triangle
Using the area formula for a triangle with base b=28 cm and height h=13 cm: Area=21×b×h=21×28×13=14×13=182 sq cm.
Area=21×28×13=182 sq cm
B is correct because the base of the triangle is 28 cm and the height is 13 cm, giving an area of 182 sq cm.
Always remember the relation between diagonal and side of a square (d=s2) as it frequently simplifies geometry problems in quantitative aptitude tests.