Step-by-step explanation:
Sin<D = Opposite / Hypotenuse
Opposite - EC
Hyp - DE
Sin<D = EC/DE = x/9
we need x to find <D.
so -->Use pythagorean theorem.
DE^2 = EC^2 + DC^2
DE = 9 DC = 7 EC = ?
EC^2 = DE^2 - DC^2 rearranged.
= 9^2 - 7^2
= 81 - 49
EC^2 = 32 Put both sides under square root.
√(EC^2) = √32
EC = 4√2 ~ 5.65.
We now have X which was representing the unknown side EC.
Sin<D = EC/DE = 5.65/9 = 0.627
To find <D Take the sine inverse of of 0.627.
<D = Arcsin(0.627) = 38.82°.
We now know <D. It's <E's turn.
A right angle triangle has a summation of interior angles of 180°.
thus, <em><D + <C + <E = 180°</em>
38.82° + 90° + <E = 180°
128.82° + <E = 180°
subtract both sides by 128.82°
0 + <E = 180° - 128.82°
<em><E = 51.</em><em>2</em><em>°</em>
