Q. In the given figure ABPC is a quadrant of a circle of radius 14 cm and a semicircle drawn with BC as diameter. Find the area of the shaded region.
Q. Water in a canal, 6 m wide and 1.5 m deep, is flowing with a speed of 10 km/h. How much area will it irrigate in 30 minutes. If 8 cm of standing water is needed?
Q. A cone of maximum size is carved out from a cube of edge 14 cm. Find the surface area of the remaining solid after the cone is carved out.
Answers
sorry do not know the answer
Ans.1. Area of shaded region = area of semicircle of diameter BC - {area of quadrant of radius AB /AC - area of ∆ABC }
So, area of semicircle of diameter BC = 1/2 πr²
= 1/2 × 22/7 × 7√2 × 7√2 [ ∵ BC is hypotenuse of right angle ∆ABC , here AB = BC = 14 so, BC = 14√2 = 2 × radius ⇒ radius = 7√2 ]
= 11 × 7 × 2 = 154 cm²
area of quadrant of radius AB/AC = 1/4 πr²
= 1/4 × 22/7 × 14 × 14
= 22 × 7 = 154 cm²
area of ∆ABC = 1/2 height × base
= 1/2 × 14 × 14 = 98 cm²
Now, area of shaded region = 154cm² - { 154cm² - 98cm²} = 98cm²
Hence, area of shaded region = 98 cm².
Ans.2. Speed of flowing of water from canal is 10km/h , means length of water flows in 1 hour = 5 km , so length of water flows in 30 minutes = 5km
Now, volume of water flowing from canal = length of water flows in 30 minutes × breadth of canal × deep of canal
= 5000m × 6m × 1.5m = 45000 m³
Let area of field = x m²
Then, volume of water irrigates into the field = area of field × height of water during irrigation
= x m² × 8× 10⁻² m = 0.08x m³
Now, volume of water flowing from canal = volume of water in field
45000 m³ = 0.08x m³
x = 562500 m²
We know, 1 hectare = 10000 m²
So, area of field in hectare = 562500/10000 = 56.25 hectares.
Ans.3. The cone will have a diameter of 14 cm and height of 14 cm. (Radius = 7cm)
Slant height of cone = √(14² + 7²) = 15.652 cm
Surface area = 22/7 x 7 x 15.652 + 22/7 x 7² = 498.35 cm²
Surface area of solid remaining solid = Total surface area of the cube - area of circle where the cone was carved out + curved surface area of cone (hole remaining in the cube)
= 14x14x6 - 22/7x7² + 22/7x7x15.652
= 1366.344 cm²
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