Question 1138457
1. Find the largest angle of the triangle whose sides are of length 2cm, 4cm, 
5cm.
The largest angle is opposite the longest side.
Use the Cosine Law.
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2. If sin x =3/5 and x is acute,find the value of tan 2x and tan x/2. 
3. Find all the angles 0° and 360° whose sine is +.5.
you have to know that.
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4. Find all the angles between 0° and 360° whose tangent is 1.5.
Use a calculator to find the angle in Q1.
Then add 180 degs for the angle in Q3.
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5. By means of a right-angle isosceles ∆, deduce that
Sin 45°=cos45°=1/√2.
Prove that cos(45°+A)=1/√2(cosA-sinA) and sin(45°+A)=1/√2(cosA+sinA). 
Deduce cos A = 1/√2{cos(45°+A)+sin (45° + A)} and the corresponding result 
for sin A.