D. Icosahedron
<span>In geometry, an icosahedron is a polyhedron with 20 faces. </span>
Answer:
60°
Step-by-step explanation:
The radius of the circle is given as 7 ( centre of circle to point C )
The other radius is also 7 ( from centre to point D)
CD = 7
The triangle is therefore equilateral ( all 3 sides = 7 )
The angles of an equilateral triangle are equal and measure 60°
Hence mCD = 60°
It’s option D.
Hope this helps and have a nice day
Second degree equations always have two (not necessarily different) solutions. We are told that 9 is one solution to w² - 81 - 0. To find the other, we can solve it for w and look for both.
w² - 81 = 0
w² = 81
w = √81
w = 9 OR w = -9
When solving by square roots, you need the solution and its opposite. That's because while 9 * 9 = 81, (-9) * (-9) = 81 as well.
The other solution is -9.
N - 14 = 7
n = 21
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