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knight247
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What is the radius of the incircle of the triangle whose sides measure 5, 12 and 13 units?
(A)2 units
(B)12 units
(C)6.5 units
(D)6 units
(E)7.5 units
Pretty straight forward problem. The triangle is a right triangle. For a right triangle, the radius of the incircle
r=Sum of perpendicular sides-hypotenuse/2 and u get the answer A.
Also,
What is the measure of the radius of the circle that circumscribes a triangle whose sides measure 9, 40 and 41?
(A)6
(B)4
(C)24.5
(D)20.5
(E)12.5
Another Pythagorean triplet with 41 as hypotenuse
In a right triangle, the radius of the circle that circumscribes the triangle is half the hypotenuse.
r=hypotenuse/2. Which gives the answer D
However, I remember these formulas from my school/college days and I don't recall seeing them in any of the gmat books I've been thru. It took me about 10-15 mins each to try and deduce/recall these formulas from memory. I've been thru the Manhattan gmat geometry guide 4th edition and there was little coverage on the circles topic. I guess my question is, are such problems tested frequently on the gmat. And should I be referring to a different theory book for comprehensive coverage on geometry eg Veritas Prep or Ez Solutions? Thanks
(A)2 units
(B)12 units
(C)6.5 units
(D)6 units
(E)7.5 units
Pretty straight forward problem. The triangle is a right triangle. For a right triangle, the radius of the incircle
r=Sum of perpendicular sides-hypotenuse/2 and u get the answer A.
Also,
What is the measure of the radius of the circle that circumscribes a triangle whose sides measure 9, 40 and 41?
(A)6
(B)4
(C)24.5
(D)20.5
(E)12.5
Another Pythagorean triplet with 41 as hypotenuse
In a right triangle, the radius of the circle that circumscribes the triangle is half the hypotenuse.
r=hypotenuse/2. Which gives the answer D
However, I remember these formulas from my school/college days and I don't recall seeing them in any of the gmat books I've been thru. It took me about 10-15 mins each to try and deduce/recall these formulas from memory. I've been thru the Manhattan gmat geometry guide 4th edition and there was little coverage on the circles topic. I guess my question is, are such problems tested frequently on the gmat. And should I be referring to a different theory book for comprehensive coverage on geometry eg Veritas Prep or Ez Solutions? Thanks
