Use the calculator here to get
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Triangle area is (1/2)*base length*height. here: base length = 12 and height = 7. You can crunch the numbers!
It isn't "in" it is "ln" or "Ln". "ln" has a lower case "l" not a lower case "i". It represents logarithm to the base e (e = 2.718281828....)
The complete circumference is 2*pi*r where r is the length of the minute hand.
One quarter of the circumference equals 15 cm so:
2*pi*r/4 = 15
r = 2*15/pi so r = 9.5 cm to 1dp
Presumably you mean OC = OA = 16.
If so you have a right-angled triangle with hypotenuse = 16 + 18 → 34
Use Pythagoras: AB = sqrt(34^2 - 16^2) → 30
After each press the new copy would be reduced to 0.88 times its size before the press.
After 5 presses the size would be 8*0.88^5 = 4.22 inches
This goes to log(2)/log(0) and since log(0) is -infinity the limit goes to 0.
cos(3pi/2 radians) = cos(270°) = cos(-90°) = cos(90°) = 0
See my (corrected) answer at http://web2.0calc.com/questions/if-a-b-c-pi-amp-cosa-cosb-cosc-then-prove#r2
My reply above that part (i) is incorrect is itself incorrect!! (I forgot about the cos A = cos B*cos C bit!)
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