HELP=HELP TRIG QUESTION
Favorites|Homepage
Subscriptions | sitemap
HOME > > HELP=HELP TRIG QUESTION

HELP=HELP TRIG QUESTION

[From: ] [author: ] [Date: 13-04-21] [Hit: ]
In the 1st, mark angle A and mark Opp = 1, Hyp = 10, so by the Theorem of PythagorasADJ = sqrt (100 - 1) = sqrt99 so cos A = (sqrt99)/10 = 3rt11/10.Do exactly the same with a second triangle having an acute angle B and mark Adj = 4, hyo = 10 so sinB = (2rt21/10);do the same again for sinC(rt51/10).......
angles A B C are acute angles such that sin A = 0.1 cos B = 0.4 sin C = 0.7
without finding the angles A B C use the addition formula to calculate to 2 decimal places

sin(A+B) cos(B-C)

the answers are 0.95 and 0.93 please show workings

-
First, we find cosA, sinB, sinC. In each case draw a right-angled triangle. In the 1st, mark angle A and mark Opp = 1, Hyp = 10, so by the Theorem of Pythagoras ADJ = sqrt (100 - 1) = sqrt99 so cos A = (sqrt99)/10 = 3rt11/10. Do exactly the same with a second triangle having an acute angle B and mark Adj = 4, hyo = 10 so sinB = (2rt21/10); do the same again for sinC (rt51/10). Now use Sin(A + B) = sinAcosB + cosAsinB ; put in the values from above to get sin(A + B) = (1/10)*(4/10) + (3rt11/10)(2rt21/10) - at this point, use your calculator, and you should get the required answer. Cos(B - C) = cosCcosB + ssinCsinB. Do exactly the same here. Rounf off in both cases.

-
sin A = 0.1 cos A = sqrt 0.99 cos B = 0.4 sin B = sqrt 0.84 sin C = 0.7 cos C = sqrt 0.51
sin(A + B) = sin Acos B + cosAsin B = 0.1 x 0.4 + sqrt 0.99 x sqrt 0.84 = 0.04+ 0.912 = 0.952 = 0.95
cos(B-C) = cosBcosC + sinBsinC = 0.4sqrt0.51 + 0.7sqrt0.84 = 0.2857 +0.6416=0.9273 =0.93

-
Do it urself noob
1
keywords: HELP,QUESTION,TRIG,HELP=HELP TRIG QUESTION
New
Hot
© 2008-2010 http://www.science-mathematics.com . Program by zplan cms. Theme by wukong .