42.
Step 1: Rewrite all numbers as powers of their prime factors.
23×(22)−1×7−272×(72)−2×(2×7)
Step 2: Apply exponent rules (am)n=amn and am×an=am+n.
23×2−2×7−272×7−4×21×71
23−2×7−221×72−4+1
21×7−221×7−1
Step 3: Apply exponent rule anam=am−n.
21−1×7−1−(−2)
20×7−1+2
1×71
7
The simplified value is 7.
43.
Step 1: Convert decimals to fractions or powers of 10.
0.95×0.0018×160.024×0.00057=10095×1000018×16100024×10000057
=1000×100000×95×18×1624×57×100×10000
=10×10×95×18×1624×57
Step 2: Simplify the numerical part.
=100×95×18×1624×57
Divide 24 by 16: 24/16=3/2.
=100×95×18×23×57
Divide 57 by 18: 57/18=(3×19)/(3×6)=19/6.
=100×95×6×23×19
Divide 3 by 6: 3/6=1/2.
=100×95×2×219
Divide 19 by 95: 19/95=1/5.
=100×5×2×21
=100×201
=20001
The value is 20001.
44.
Step 1: A regular heptagon has 7 equal sides and 7 equal interior angles. It can be divided into 7 congruent isosceles triangles, with their vertices at the center O.
Step 2: Calculate the angle at the center for each triangle.
θ=7360∘
Step 3: The area of one such triangle (e.g., △OAB) is given by the formula:
Area of △OAB=21r2sin(θ)
Given radius r=OB=10 cm.
Area of △OAB=21(10cm)2sin(7360∘)
Area of △OAB=21×100cm2×sin(51.42857∘)
Area of △OAB=50cm2×0.78183
Area of △OAB≈39.0915cm2
Step 4: Calculate the total area of the heptagon.
Area of heptagon=7×Areaof△OAB
Area of heptagon=7×39.0915cm2
Area of heptagon≈273.6405cm2
Step 5: Round to 2 decimal places.
Area of heptagon≈273.64cm2
The area of the heptagon is 273.64cm2.
45.
a) Find the number of sides of the polygon;
Step 1: Use the formula for the sum of interior angles of a polygon with n sides:
Sum of interior angles=(n−2)×180∘
Step 2: Set the formula equal to the given sum and solve for n.
(n−2)×180∘=1440∘
n−2=1801440
n−2=8
n=8+2
n=10
The number of sides of the polygon is 10.
b) the size of each exterior angle of the polygon.
Step 1: The sum of the exterior angles of any convex polygon is 360∘.
Step 2: For a regular polygon with n sides, each exterior angle is equal.
Each exterior angle=n360∘
Step 3: Substitute n=10.
Each exterior angle=10360∘=36∘
The size of each exterior angle is 36∘.
c) the number of triangles the polygon can be divided into
Step 1: A polygon with n sides can be divided into (n−2) triangles by drawing diagonals from one vertex.
Step 2: Substitute n=10.
Number of triangles=10−2=8
The number of triangles the polygon can be divided into is 8.
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