Circle the problems below that you could use mental math to solve.

Mathematics

1 answer:

SashulF [63]2 years ago

4 0

I think this is more of an opinion question. What someone could solve mentally may not be the same as someone else's.If it were my worksheet, I'd circle all of them but it may be different for you.
At your level, I'd probably circle:
54 - 10
93 - 20
and 39 - 2

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Given: ΔАВС, m∠ACB = 90°,m∠ACD = 30°,AD = 8 cm. Find: CD, Perimeter ΔABC <br><br> Please solve!

sukhopar [10]

If m ACD = 30 => m DCB = 60.
In triangle ACD:
$sin 30^{o}=sin \frac{AD}{AC} =\ \textgreater \ \frac{1}{2} = \frac{8}{AC} =\ \textgreater \ AC=16
$
$CD= 8 \sqrt{3}$
$BC= 16\sqrt{3}$
AC^{2}+CB^{2}=AB^{2} => AB= $\sqrt{1024}$ =32.
=> P=16+32+ $16 \sqrt{3}$ =48 + $16 \sqrt{3}$ .