Question
The length of a side of an equilateral triangle is 18
cm. The area (in cm²) of the region lying between the circumcircle and the incircle of the triangle is [use use π =22/7]Solution
Side of the equilateral triangle = 18 cm Radius of circum - circle R = 18/√3 cm Radius of in - circle r = 18/2√3 = 9/√3 cm Area between the circum - circle and in – circle = π (R2 – r²)  = π (R+ r) (R-r) = (22/7) × (18/√3 + 9/√3) (18/√3-9/√3) = (22/7) × 27/√3 × 9/√3 = (81×22)/7 = 1782/7 cm² =254(4/7) cm2
1.2Â Â Â Â Â Â Â 4.2Â Â Â Â Â Â Â Â ? Â Â Â Â Â Â Â Â Â Â Â 18.2Â Â Â Â Â Â Â 33.2 Â Â Â Â Â Â 56.2
...5, 14, 41, 122, 365, 1094, ?
If 2.5 3.5 x 30 124 625
Then, x ² - 1 - 2x = ?
...157, 159, 189, 319, ‘?’, 1 407 , 2749 Â
1335Â Â Â Â Â Â 737Â Â Â Â Â Â Â Â 355Â Â Â Â Â Â Â Â 141Â Â Â Â Â Â Â Â 47Â Â Â Â Â Â Â Â Â Â ?
...8, 9, 15, ?,82.5, 250.50
22 44 176 1078 8448
...3 15 35 63 99 ?
95    216    72    241    ?    270
If   314     306      x      269       394    178    1480
Then, 1/3 x + 2x - x = ?
...
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